Chemistry Perfect Score Module Form 4 2011 No Logo

Form 4 Score A+ Module

CHEMISTRY SCORE A+ MODULE FORM 4

SET 1

1. The Structure of Atom 2. Chemical Formulae and Equations

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STRUCTURE OF THE ATOMS 1. 2. 3. Matter is anything that . and has . The particle theory of matter state that matter is .. Type of particle Example

4. Property Diagrammatic representation of the particles in each of the physical states Arrangement of particles. Forces of attraction between particles Movement of particles Energy content Solid Liquid Gas

5.

Subatomic particles in an atom. Subatomic particle Symbol Relative mass Charge

6.

Isotope are atoms with the same

but different

. 7. The isotopes of an element have same ... but different because they have . 8. Compare and contrast the atoms below.12 14

C6 6

C

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9.

Complete the table below. Uses

Isotope Carbon-14

Cobalt-60

Sodium-24

PAPER 2 : STRUCTURE 1. (a) Diagram 1.1 shows the results of an experiment to investigate the movement of bromine particles in air.

Air

Gar jar Cover

Bromine vapour

Reddish brown vapour spreads throughout both gas jars within 10 minutes

Diagram 1.1

Cover removed

(i)

State the name of the process involved in this experiment. ...... [1 mark] State the type of particles present in bromine gas. ..... [1 mark]

(ii)

(iii)

Explain the observation in this experiment based on the kinetic theory of matter. .... .... .... [3 marks]

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Temperature

83 Diagram 1.2

R

T

Time, s(b) Diagram 1.2 shows a graph of temperature against time when solid X is heated? (i) State the melting point of X. ... [1 mark] What happens to the temperature while the substance changes state? Explain. ...... ...... ...... [2 marks] (iii) Explain the movement of particles X between R and T during heating. ... ... [2 marks]

(ii)

Glass wool soaked in concentrated ammonia solution

Glass wool soaked in concentrated hydrochloric acid

Diagram 22. Diagram 2 shows the set-up of apparatus to investigate the reaction between concentrated hydrochloric acid and concentrated ammonia solution to form substance X. Based on the information, answer the following questions. (a) (i) What is the observation in the glass tube? ... [1 mark]

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(ii)

Name substance X ..... [1 mark]

(iii)

Name the process occurs in the glass tube. ..... [1 mark]

(b)

Which gas diffused faster? Why? ...... ...... [2 marks]

(c)

Write the chemical equation for the reaction in the experiment. ..... [1 mark]

3.

Table 3 shows proton number and nucleon number for atom W, X and Y. Atom W X Y Proton number 11 17 17 Nucleon number 23 35 37

Table 3(a) (i) What is meant by proton number? .................................................................................................... [1 mark] What is the number of neutron in atom W ?

(ii)

(b)

...................................................................................... [1 mark] Which atoms are isotopes? Explain why. ............................................................................................................................................................ ........................................................................................................................................................... [2 marks] Write the electron arrangement of atom X . .......................... ................................................................................................................................... [1mark]

(c)

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(d)

(i)

Draw the electron arrangement of atom Y. In your diagram , show the number of proton and the number of neutron in the nucleus.

[2 marks] (ii) What is the number of valence electron of atom Y?

..................................................................................................................................................... [1 mark] (iii) Write the formula of ion Y. ..................................................................................................................................................... [1 mark] (e) Write the symbol of atom X in the form ofA Z

X.

.............................................................................................................................................................. [1 mark] 4. (a) Diagram 4.1 shows the set-up of an experiment to determine the melting point of solid X.

Thermometer

Water

Diagram 4.1 The temperature of X is recorded at 30 seconds intervals as shown below.

Time/second Temperature/oC

0 70

30 77

60 80

90 80

120 80

150 82

180 85

210 95

(i)

Plot the graph of temperature against time for the heating of X on the graph paper. [3 marks]

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Graph temperature against time

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(ii)

On the graph that you have drawn in (a), label the melting point of substance X. [1 mark]

(iii)

Explain why the temperature remains constant from 60 s to 120 s? ....................................................................................................................... .................................................................................................................................. [2 marks] Draw the arrangement of particles in X at 85oC

(iv)

[ 1 mark ] (b) Why has the solid X in the boiling tube be stirred constantly with the thermometer during the experiment? .................................................................................................................... [1 mark] Why solid X is not directly heated without using water bath? ....................................................................................................................... [1 mark] 5. Table 5 shows four substances and their respective formulae. Substance Iodine Copper Ethanol Potassium chloride Table 5 (a) State 2 substances that consist of molecules. ..................................................................................................................... [2 marks] Which of the following substances has a highest melting point? ............................................................................................................................... [1 mark] State the substance that can conduct electricity in the solid state. ............................................................................................................................... [1 mark] Name the particles present in potassium chloride. ............................................................................................................................... [1 mark] Chemical formula I2 Cu C2H5OH KCl

(c)

(b)

(c)

(d)

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PAPER 2 : ESSAY 6. Diagram 6.1 shows an atom of an element based on the model by James Chadwick.

Electron Proton Neutron Diagram 6.1(a) Compare the relative mass and the charge of two of the subatomic particles in diagram 6.1. [4 marks]

7p 7n

Diagram 6.2Diagram 6.2 shows an atom of element X. (b) (i) Describe fully the atomic structure shown in diagram 7.2. [4 marks] (ii) Write a symbol for the element in the form of

A Z

X[2 marks]

(c)

Graph 6.3 shows the heating curve of element Y.

Temperature /o C

Melting point

Graph 6.3 to t1 t2 t3 Time, minutes

Describe the graph in term of states of matter, particles arrangements and changes in energy. [10 marks]

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7

(a)

What is meant by melting point? During the melting of naphthalene, the temperature remains constant even though heat is applied. Explain why. [4 marks] Condensation is the process where a gas changes to its liquid state at a certain temperature and pressure when it is cooled.

(b)

Describe the change of the kinetic energy, arrangement and the forces of attraction between the particles at the following states: (i) (ii) (iii) Before condensation During condensation After condensation [10 marks]

(c)

Diagram 7 shows the electron arrangement of ion Y3+. ee e e e 14 n e ee e e 3+ n neutron e electron Diagram 7 [2 marks]

(i) Calculate the nucleon number of atom Y. (ii) Y reacts with oxygen to form oxide Y, with the formula Y2O3. The chemical equation for reaction Y with oxygen is show as: 4Y + 3O2 2Y2O3. Given that the relative atomic mass of Y = 27 and O = 16.

Calculate the mass of oxide Y, Y2O3 formed when 10.8 g Y is completely burnt in oxygen. [4 marks]PAPER 3 : STRUCTUREGas jar cover Gas jar Bromine vapour Potassium manganate(VII) Jelly Water

A

B

Diagram 8 Page 10 / 96

C


8.

A group of students set up the apparatus for an experiment as shown in diagram 8. The result is obtained by the students are shown in table 8. Experiment A B C (a) Observation After a few minutes the gar jar was filled with a reddish brown gas. After a few hours, the water turns purple. After a few days, the jelly turns purple.

State the aim of the experiments carried out. ................................................................................................................................

(b)

State the hypothesis of the experiments. ............................................................................................................................... ...............................................................................................................................

(c)

State (i) The manipulated variable. ..................................................................................................................... The responding variable. ..................................................................................................................... (iii) The fixed variable of the experiments. .....................................................................................................................

(ii)

(d)

Based on the observation, arrange the three states of mater in a sequence to show their speed in increasing order. .............................................................................................................................. Based on the rate of the movement of the particles, describe the arrangement of the particles in the three states of matter. .............................................................................................................................. .............................................................................................................................. ..............................................................................................................................

(e)

(f)

Give the daily application of the process in one of the above experiment. ..............................................................................................................................

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CHEMICAL FORMULA AND EQUATION 1. Write the chemical formula of the compound in the table below. Ion Sodium Magnesium Lead(II) Copper (II) Iron (II) Iron (III) Aluminium 2. Write balanced chemical equation for the following chemical reactions. (a) Heat solid of copper (II) carbonate . Nitric acid reacts with sodium hydroxide . Hydrochloric acid reacts with zinc metal . Copper(II)nitrate reacts with magnesium . Chlorine gas reacts with lithium hydroxide . Hydrogen gas reacts with lead(II) oxide . 3. Avogadro constant, NA is defined as the number of particles in one mole of a substance [1 Mol any substance consist of 6.02 X 1023 particles]. Calculate the number of particles in: (a) 0.1 mol of calcium Chloride Nitrate Hydroxide Sulphate Carbonate oxide

(b)

(c)

(d)

(e)

(f)

(b)

1.5 mol of iron

(c)

2.0 mol of oxygen gas

(d)

1.5 mol of helium

(e)

2.0 mol hydrogen chloride

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4.

Calculate the number of moles of the following substances. (a) 6.0 x 1023 aluminium 1.8 x 1021 argon 1.2 x 1023 bromine gas 2.4 x 1020 carbon dioxide 3.0 x 1023 ammonia

(b)

(c)

(d)

(e)

5.

Calculate the mass of following substances. b) 2.5 moles of oxygen gas

a) 1.5 mol of chlorine gas

c) 2.0 moles of sulphuric acid

d) 0.5 moles of ammonia, NH3

e) 2.5 moles of lead (II) carbonate

f) 0.5 moles copper(II) nitrate, Cu(NO3)2

Molar volume: The volume of one mole of the gas [22.4 dm3 mol-1 at STP, standard temperature and pressure] [24 dm3 mol-1 at Room condition] 6. Calculate the volume of gases below. (a) 0.5 mol of chlorine at STP.

(b)

0.2 mol of carbon dioxide at Room condition.

(c)

1.5 mol of methane at room condition.

(d)

0.5 mol of helium at room condition.

(e)

2.5 mol of ammonia at STP

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7.

Calculate the number of moles of the gases below. (a) 250 cm3 of carbon dioxide in room temperature. (b) 500 cm3 of hydrogen sulfide at STP. (c) 200 cm3 of hydrogen chloride in room temperature. (d) 750 cm3 of neon in room temperature. (e) 300 cm3of ammonia at STP.

8.

Magnesium powder reacts with hydrochloric acid to produce salt and hydrogen gas. (a) Write the balance chemical equation for this reaction. . If 2.4 g of magnesium powder is added into excess hydrochloric acid, calculate, (i) The mass of salt formed.

(b)

(ii) The volume of hydrogen gas liberated at room temperature.

9.

Lead is extracted according to the following equation. C (a) (b) + PbO CO2 + Pb

Write the balanced chemical equation for the reaction. Determine the number of moles of lead extracted from 0.5 mole of lead (II) oxide.

(c)

Calculate the number of moles of carbon required to extracts 0.5 mole of lead(II) oxide.

(d)

What is the mass of lead are produced if 44.6 g of lead (II) oxide is heated with excess carbon. [ RAM : Pb = 207, O = 16, C = 12 ]

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10.

Excess sodium carbonates is added into 50 cm3 of 0.5 mol dm-3 copper(II) chloride. The chemical equation for the reaction is as follows: CuCl2 + (a) (b) Na2CO3 NaCl + CuCO3

Balance the chemical equation for the reaction. Calculate the mass of copper(II)carbonate.

11.

5g of calcium carbonate is added to excess hydrochloric acid. (a) Write balanced chemical equation for the reaction. .. (b) Determine the volume of carbon dioxide gas evolved at room temperature

12.

When sodium bicarbonate is heated, it decomposed to sodium carbonate, carbon dioxide and water. (a) Write a balanced chemical equation for the decomposition of sodium bicarbonate on heating. ... (b) If 8.4 g of sodium bicarbonate decomposes, calculate (i) The volume of carbon dioxide gas evolved at room temperature.

(ii) The mass of sodium carbonate formed.

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Concentration of acids and alkalis (STOICHEIOMETRY) The concentration of a solution is the mass (in gram) or the number of mole of solute dissolved in a solvent to form 1.00 dm3 of solution. Concentration, g dm-3 Concentration, mol dm-3 / molarity Mass of solute, g Volume of solution , dm3 Number of mole of solute, mol Volume of solution , dm3

Titration Formula MaV2 = a MbVb bMb Vb b = Concentration of the alkali = Volume of used alkali = the number of mole of alkali

Ma Va a

= Concentration of the acid, = Volume of used acid, = the number of mole of acid,

Dilution M1V1 = M2V213. 100cm3 of HCl 2.0 mol dm-3 reacts completely with excessive zinc powder. Calculate the volume of gas released at room temperature? (Molar volume = 24 dm3 at room temperature).

14.

5 g of Calcium carbonates dissolves in 100 cm3 of nitric acid 0.5 mol dm-3 to produce salt, carbon dioxide gas and water. (i) Write out the equation. .. (ii) Calculate the moles of calcium carbonates used. (RAM Ca =40, C = 12, O = 16).

(iii) Calculate the moles of acid.

(iv) Calculate the volume of gas produced.

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15.

X g sodium carbonate reacts completely with 100 cm3 hydrochloric acid 1.0 moldm-3 to produce sodium chloride, carbon dioxide and water. Find X. (relative atomic mass: Na =23, C = 12, O = 16)

16.

10 g of copper(II) oxide reacts completely with 100 cm3 hydrochloric acid to form copper(II) chloride and water. Calculate the molarity of acid used. (JAR Cu =64, O = 16 )

17.

The concentration of sodium hydroxide solution is 8.0 g dm-3. (a) What is the molarity of the solution?

(b) What is the molarity of the solution produced when 100 cm3 of distilled water is added to 50 cm3 of this solution?

18.

In the titration experiment, 25.0 cm3 of 2.0 mol dm-3 sodium hydroxide solution is titrated with sulphuric acid from a burette. 18.50 cm3 of sulphuric acid is needed for complete neutralization. (a) Write a balanced chemical equation for the neutralization. (b) Calculate the number of mole of sodium hydroxide used in this experiment.

(c) Calculate the number of moles of sulfphuric acid needed to exactly neutralize 25.0 cm3 of 2.0 mol dm3 sodium hydroxide.

(d) Calculate the molarity of sulphuric acid.

19.

1.25 mol dm-3 hydrochloric acid reacts completely with 25.0 cm3 of 1.0 mol dm-3 sodium carbonate. (a) Write a balanced chemical equation for this reaction. (b) Calculate the number of mole of sodium carbonate used in this experiment. (c) Calculate the volume of hydrochloric acid needed to exactly neutralize 25.0 cm3 of 1.0 mol dm-3 sodium carbonate.

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PAPER 2: STRUCTURE 1. Diagram 1 shows the set-up of the apparatus for an experiment to determine the empirical formula of an oxide of copper.

Oxide of copper

Dry hydrogen gas

Heat Diagram 1Table 1 shows the results of an experiment after heating, cooling and weighing are repeated until a constant weight is obtained. Substance Mass of combustion tube + porcelain dish Mass of combustion tube + porcelain dish + oxide of copper Mass of combustion tube + porcelain dish + copper Mass(g) 18.75 g 20.75 g 20.35 g

Table 1(a) What is meant by empirical formula? ... [1 mark] Based on Table 5 results, (i) Calculate the mass of copper and the mass of oxygen used in the experiment.

(b)

[2 marks] (ii) Calculate the mole ratio of copper atoms to oxygen atoms. Given that the relative atomic mass of Cu, 64; O ,16.

[2 marks] (iii) State the empirical formula of this oxide of copper.

. [1 mark] (iv) Write the chemical equation for the reaction in this experiment. ... [1 mark]

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(c)

Describe the steps that should be taken to ensure that all the air in the combustion tube has been expelled , before any heating is carried out. .... . . ... [3 marks]

2.

(a)

Culculate the relative molecular or formula masses of the following substances. (i) Ethanol, C2H5OH. Given that relative atomic mass of H = 1, C = 12, O = 16.

[1 mark] (ii) Zinc nitrate, Zn(NO3)2 Given that relative atomic mass of O = 16 , N = 14, Zn = 65 .

[1 mark] (b) A closed glass bottle contains 4 mol molecules of oxygen, O2. (i) What is the number of oxygen molecules in the bottle?

[1 mark] (ii) How many oxygen atoms are there in the bottle?

[1 mark] (c) Find the number of moles of atoms in a sample containing 9.03 1020 atoms of copper.

[1 mark] (d) Calculate the mass, in gram, of 3.5 moles of copper(II) carbonate, CuCO3. Given that relative formula mass of CuCO3 = 124

[1 mark] (e) When silver carbonate, Ag2CO3 is heated, it will decompose to produce silver metal, carbon dioxide gas and oxygen gas as shown in the equation below. 2Ag2CO3(s)

4Ag(s) + 2CO2(g) +

O2(g)

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A student heats 8.28 g silver carbonate. Calculate the volume of carbon dioxide gas, CO2 collected at room temperature. Given that relative atomic mass of C = 12, O =16, Ag = 108,

[3 marks] 3. Diagram 3 shows 3.1 g of copper (II) carbonate being heated strongly in attest tube. The gas given out is passed into limewater in a test tube through a delivery tube.

Copper(II) carbonate Heat strongly Diagram 3(a) State the observation made when copper(II)carbonate powder is heated until the reaction is complete. [1 mark] Write the chemical equation to represent the reaction that takes place. . [1 mark] Calculate the number of moles of copper(II)oxide produced.

Lime water

(b)

(c)

[2 marks] (d) Calculate the volume of gas produced at STP.

[2 marks] (e) (i) What can be observed if the product is heated in a stream of hydrogen gas? .. [1 mark] Calculate the mass of the substance produced.

(ii)

[2 marks]

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PAPER 2 : ESSAY 4. (a) The information below is regarding substance X

Carbon 85.70% Hydrogen 14.30% Relative molecular mass = 56

(i)

Determine the empirical formula of substance X. [Given that the relative atomic mass of C = 12 , H = 1] Determine the molecular formula of substance X. Based on the answers in (a)(i) and (a)(ii) , compare and contrast the empirical formula and the molecular formula. [ 8 marks]

(ii) (iii)

(b)

Magnesium can react actively with oxygen to form magnesium oxide. Describe an activity that can be carried out in the laboratory to determine the empirical formula of magnesium oxide. Include the calculations involved in your answer. Given that the relative atomic mass for O = 16, Mg = 24. [11 marks]

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PAPER 3 : STRUCTURE 5. A student carried out an experiment to determine the empirical formula of magnesium oxide. The steps and set-up of apparatus of the experiment are shown in Diagram 5. 1. The crucible and lid are weighed.lid crucible

123.3632g

digital balance

2. The crucible, lid and magnesium powder are weighed.

Magnesium powder

128.1580g

3. The magnesium powder is heated until it reacts completely with oxygen.

white fumes

heat

4. The crucible, lid and magnesium oxide are weighed when cooled.

magnesium oxide powder

131.3580g

Diagram 5

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(a)

Complete the following table by stating the observations and related inferences in the experiment. Observations (i) ................................................ .................................................... Inferences (i) ................................................................ ....................................................................

(ii) ............................................... .................................................... (iii) ) .................................................... ....................................................

(ii) ............................................................... ..................................................................... (iii) .................... ............................................... .................................................................... [6 marks]

(b)

Round off the reading to two decimal places and record it in the table below. Description The crucible and lid. The crucible, lid and magnesium powder. The crucible, lid and magenesium oxide. Mass / g

(c)

(i)

Calculate the mass of magnesium that has been used.

(ii)

Calculate the mass of oxygen which reacted with magnesium.

(iii)

Determine the empirical formula of magnesium oxide. Use the information that the relative atomic mass, O = 16, Mg = 24

(d)

The student wants to determine the empirical formula of lead(II) oxide. He used the steps and set-up of apparatus as the experiment before. Predict whether the empirical formula of lead(II) oxide can be determined. Explain your answer. ...............................................................................................................................................................

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SET 2

Periodic Table of Elements Chemical Bonds

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PERIODIC TABLE OF THE ELEMENTS Periodic Table of Elements 1 2 13 14 15 16 17 18

Transition elements

Group 1 : Alkali Metals Li Na K Rb Cs 2. 1 2. 8. 1 2. 8. 18. 1 2. 8. 18. 18. 1 2. 8. 18. 32. 18. 1

1. Each atom has one .. 2. Thats why the elements in the group have similar .. properties. 3. All atoms in the group can form ion with one positive charge. How? .. 4. The reactivity of alkali metals increases down the group. Why? Atomic size increases. Distance of valence electron from nucleus is further. Attraction between nucleus and valence electron is weaker. Easier to donate/ release the valence electron.

5. Chemical properties : Reaction With water. With oxygen. Base dissolves in water. with halogen (chlorine, bromine, iodine) Product Alkali and hydrogen gas Oxide metal / base. Alkali Salt Chemical equation 2LiOH + H2 2 Li2O (white) 2LiOH 2 LiCl (white)

2Li + 2H2O 4 Li + O2

Li2O + 2Li +

H2O Cl2

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Group 18 : Noble Gas He Ne Ar Kr Xe Rn 2 stable / duplet electron arrangement 2. 8 2. 8. 8 2. 8. 18. 8 octet electron arrangement 2. 8. 18. 18. 8 2. 8. 18. 32. 18. 8

1. Elements in this group are in the form of monatomic. 2. They are chemically inert, whereas they do not easily . , .or electrons with others. 3. This is because their outer shell is fully filled with ... electrons (except He). 4. Physical Properties : i) When going down the group, the atomic radius ... This is because .. ii) When going down the group, the melting point and boiling point ... This is because ..

Group 17 : HALOGEN F Cl Br I As 2. 7 2. 8. 7 2. 8. 18. 7 2. 8. 18. 18. 7 2. 8. 18. 32. 18. 7

1. Diatoms at room temperature. (Cl2, Br2, I2) 2. Each atom has seven .. 3. Thats why the elements in the group have similar ... 4. All atoms in the group can form ion with one ... charge. How? ....

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5.

Chemical properties: Reaction With water. With alkali. With metal (iron). Product acid salts salt Chemical equation Cl2 + H2O HCl + HOCl Cl2 + 2KOH KCl + KOCl + H2O 2Fe + 3Cl2 2FeCl3 (brownish)

6. The Melting Point and Boiling Point increases down Group 17. Why? Molecular size increases. Forces between molecules become stronger. More heat energy is needed to overcome the forces.

Elements across the Period: 1. Element Na Mg Metals Oxide Na2O Base MgO

Al

Si Metalloid SiO2

P

Al2O3 Amphoteric

P2O5

S Nonmetal SO2 Acidic

Cl

Ar

Cl2O7

2. Changes of elements when across the period atomic size decreases melting point increase then decreases electronegativity increases from metals to non-metals Chemical properties from basic to acidic. 3. Why the atomic size (atomic radius) decreases across the period? Proton numbers increase. The numbers of electrons in shells increase. The positive charges in nucleus increase. The force of attraction from nucleus towards all the electrons in the shell increases. Thus the atomic size increase. Transition elements 1. State special characteristic of transition elements and examples. Special characteristic Form coloured ions. Cu2+ 3+

Example - blue, Cr - green, Fe3+ - brown

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PAPER 2 STRUCTURE

1.

Diagram 1 shows part of the Periodic Table of the Elements A, B, C, D, E and F do not represent the actual symbol of the elements.

A B E F C D

Diagram 1 Using the letters in the Periodic Table of the Elements in Diagram 1, answer the following questions. (a) (i) State the position of element B in the Periodic Table. ... [2 marks] (ii) Choose the element which exhibit different oxidation numbers in its compounds. ... [1 mark] (b) Element E combines with element A to form a compound. (i) Write the chemical formula of this compound. ... [1 mark] (ii) State one physical property of this compound. ... [1 mark] (c) B and E have the same chemical properties. (i) Which element is more reactive? ... [1 mark] (ii) Explain your answer in (c) (i). ... ... [2 marks]

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(d)

(i)

Which element exists as diatomic molecules? ....... [1 mark]

(ii)

Name the chemical bond in these diatomic molecules. ... [1 mark]

2.

Diagram 2 shows part of the Periodic Table of the Elements. P, Q, R, S and T do not represent the actual symbol of the elements.

Group

P R S T

Q

Period

Diagram 2 (a) Using the Periodic Table of the Elements in Diagram 2, answer the following questions. (i) Choose an element that is a halogen. ....... [1 mark] (ii) Which element is monoatomic? ....... [1 mark] (iii) Which element forms an amphotheric oxide? ... [1 mark] (b) Arrange P, Q, R, S and T according to increase in size of the atoms. ............ [1 mark]

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(c)

Write the electron arrangement for an atom of element S. .... [1 mark]

(d)

Write the formula for the ion formed from an atom of element T. .... [1 mark]

(e)

Why are elements P and Q placed in the same period? .... [1 mark]

(f)

When a small piece of element R is put into water, ROH solution is formed and hydrogen gas is released. State one observation when red litmus paper is put into the water. ... [1 mark]

(g)

State the common name of the elements between Group 2 and Group 13. ...

3.

The diagram 3 shows part of the Periodic Table of the Elements. A, B, C, D, E, F and G do not represent the actual symbol of the elements.

A D F G

B E

C

Diagram 3 Using the letters in the Periodic Table of the Elements in Diagram 3, answer the following questions (a) Write the formula for the ion formed from an atom of (i) element D ... [1 mark]

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(ii)

element B .. [1 mark]

(b)

F is a reactive metal that is situated in Group 1. (i) Give the number of electrons in ion F+? .. [1 mark] (ii) What is the electron arrangement of ion F ? ... [1 mark]+

(c)

Which of the elements can be used as a catalyst? .... [1 mark]

(d)

Element D reacts with element E to form a compound (i) Write the chemical formula of this compound ... [1 mark] (ii) Draw the diagram of the electron arrangement for the compound formed between D and E.

[2 marks] (iii) State one condition by which the compound in (d) (ii) conducts electricity? Explain your answer. ... ... [2 marks]

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PAPER 2 ESSAY

4.

Diagram 4.1 and 4.2 show the diagrams of the electron arrangement for atoms of two elements from Group 17 in the Periodic Table of the Elements.

Diagram 4.1 (a) Based on Diagram 4.1 (i)

Diagram 4.2

Write the electron arrangement for the atom of the element and name the element. [2 marks]

(ii)

Write a chemical equation for the reaction between this element and sodium hydroxide. [3 marks]

(b)

Compare the attractive forces between the nuclei and the valence electrons in the atoms in Diagram 4.1 and Diagram 4.2 and relate this to their respectively reactivity. [6 marks]

(c)

Another element in Group 17 is a black coloured solid. Predict the reactivity of this element in its reaction with sodium hydroxide compared to that of the element in the Diagram 4.2. [1 mark]

(d)

Diagram 4.3 shows the set up of the apparatus to investigate the reaction of an element from Group 17 with iron metal.

Iron wool Chlorine gas Diagram 4.3 Part A Part B Sodium hydroxide solution

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(i)

State two precautions that must be taken while carrying out the experiment. [2 marks]

(ii)

Describe and write the chemical equations for the reactions that occur in Part A and Part B. [6 marks]

PAPER 3 STRUCTURE 5. An experiment is carried out to investigate the statement above. Table 5 shows the apparatus set up and the observations for the experiment to determine the reactivity of the Group 1 elements based on their reactions with water. Apparatus set-up Observation towards the metal

Lithium))

water

Lithium moves slowly on the surface of the water with a hiss sound.

Potassium)) ) ) )))

water

Potassium moves vigorously and randomly on the surface of the water with a hiss sound.

sodium

)) )

water

Sodium moves quickly and randomly on the surface of the water with a hiss sound.

Table 5(a) State the variables that are involved in the experiment. Name of variables Action to be taken (i) Manipulated variable: (i) The way to manipulate variable:

(ii) Responding variable:

(ii) What to observe in the responding variable:

(iii) Controlled variable:

(iii) The way to maintain the controlled variable:

[6 marks]

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(b)

State one hypothesis for the experiment. .......................... ...................................... [3 marks]

(c)

State the operational definition for the reaction. .......................... [3 marks]

(d) Based on the observations in the figure above, arrange lithium, potassium and sodium in the descending order of reactivity of metals towards water.

Descending order of reactivity of metals towards water. [3 marks] (e) Solution X was produced from the reaction of potassium with water. Classify the ions that exist in solution X into positive ions and negative ions. Positive Ions Negative Ions

[ 3 marks]

PAPER 3 ESSAY 6.

The reactivity of the alkali metals increases as you go down the group

Refering to the statement above, plan an experiment to prove it true by using the reactions of lithium, sodium and potassium with water. Your planning must include the following items: (a) (b) (c) (d) (e) Problem statement All variables involved List of materials and apparatus Experimental procedure Tabulation of data [17 marks]

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CHEMICAL BONDS FORMATION OF IONS Cations

Releases 1 electron

+ Half equation: Li Li+ + e

Lithium atom, Li

Lithium ion, Li+ 2+ Half equation: Mg Mg2+ + 2e

Releases 2 electrons

Magnesium atom, MgAnions

Magnesium ion, Mg2+

Receives 1 electron Half equation: F+e FFluorine atom, F Fluoride ion, F2Receives 2 Half equation: O + 2e O2-

Oxygen atom, O

Oxide ion, O2-

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FORMATION OF IONIC BONDS a) Formation of sodium chloride compound, NaCl

+ +

-

Sodium atom

Chlorine atom

Sodium ion

Chloride ion

Explanation: The electron arrangement of sodium atom is 2.8.1 and chlorine atom is 2.8.7 To achieve octet electron arrangement; o Sodium atom releases one electron to form sodium ion, Na+. Half equation: Na Na+ + e Chlorine atom receives one electron to form chloride ion, Cl-.

o

Half equation: Cl + e ClSodium ion and chloride ion are attracted to one another by strong electrostatic force which called an ionic bond Ionic compound NaCl is formed FORMATION OF COVALENT BONDS

Example

XX X

XX X XX XX

+Oxygen atom Oxygen atom

X X

X

X

XX

Oxygen molecule, O2

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Explanation The electron arrangement of oxygen atom is 2.6 An oxygen atom contribute 2 electron and attain / achieve the octet electron arrangement. Two oxygen atom share 2 pairs of electron to one another to form a double covalent bond A covalent molecule, O2 is formed

PAPER 2 : STRUCTURE 1. Diagram 1 shows the symbols for atom of element X, Y, and Z.

X

YYDiagram 1

ZZ

X

(a)

(i) (ii)

Write the electron arrangement of atom X. ............. Write the electron arrangement of ion X. ... Draw the diagram to show the formation of ion X

(iii)

(iv)

Write the half-equation to show the formation of ion X .. Explain the formation of ion X. What is the proton number of element Y? Write the electron arrangement of atom Y.

(v)

(b)

(i) (ii)

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(iii)

Write the electron arrangement of ion Y. .. Draw the diagram to show the formation of ion Y.

(iv)

(v)

Write the half-equation to show the formation of ion Y. ..

(vi)

Explain the formation of ion Y. . What is the proton number of element Z? ...............................................................................................................................................

(c)

(i)

(ii)

Atom of element Z has a nucleon number of 35. Calculate the number of neutrons in atom Z.

(iii)

Write the standard representation of element Z.

(d)

Element Y and Z are reacted to form a compound T. (i) Name the type of compound T. . Draw the electron arrangement for the compound T.

(ii)

(iii)

State one physical property of compound T.

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(e)

Element X can react with carbon to form a compound. [ Proton number of C = 6 ] (i) Name the type of bond in the compound formed. Draw the electron arrangement for the compound formed.

(ii)

(iii)

State one physical property of compound formed. . ..

2

Table 2 shows the proton numbers of elements A, B and C. Elements A B C Table 2 a) (i) Write the electron arrangement for atom A .... Write the electron arrangement for ion A ............ Draw the diagram to show the formation of ion A Proton Number 11 8 1

(ii)

(iii)

(iv)

Write half- equation to show the formation of ion A . Write the electron arrangement for atom B .

b)

(i)

(ii)

Write the electron arrangement for ion B. . Write half- equation to show the formation of ion B

(iii)

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c)

A and B react to form a compound ( i) What type of bond in the compound formed? ............ Draw the electron arrangement of the compound formed in (c)(i)

(ii)

(iii)

State one physical property of the compound formed

d)

C can react with B to form a compound. (i) What is the molecular formula of the compound formed? ............................................................................................. Draw the electron arrangement of the compound formed in (d)(i)

(ii)

(iii)

What is the relative molecular mass of the compound in d(i). [ Given that relative atomic mass C = 1; B= 16] ................. Name another compound that has the same physical properties as the compound formed. .............

(iv)

3

Diagram 3 shows the position of several elements P, Q, R, S, T, U and W.

P Q R S

V

T U W X

Diagram 3

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Using the symbols P, Q, R, S, T, U and W, answer the following questions. (a) Write the electron arrangement of (i) (ii) Atom R:.. Ion P:.

(b)

Explain the formation of ion U . .... (i) What is the formula for ion formed by Q .................. Write half- equation for (c) (i)

(c)

(ii)

(d)

.............. Atoms of P and U can reacted to form a compound. (i) Name the type of bond in the compound formed between atom P and U

...... (ii) Draw the electron arrangement for the compound formed.

(e)

Atom V and T can also react to form a compound. Draw the electron arrangement for the compound formed.

4.

Diagram 4 shows the chemical symbols of element sodium, oxygen, carbon and chlorine.

23

16

12

19

Na11 8

O6

C9

F

Diagram 4

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(a)

Write the electron arrangement of (i) (ii) (iii) (iv) Sodium atom:.... Oxide ion: . Carbon atom:........................................................ Flouride ion:..................................................

(b)

State the period and the Group for Flourine in Periodic Table of element (i) (ii) Period:. Group:.

(c)

Sodium atom and oxygen atom react to form a compound. (i) Name the type of bond in the compound formed when sodium react with oxygen. ... (ii) Draw the electron arrangement for the compound formed.

(d)

Carbon atom and Flourine atom can also react to form a compound. Draw the electron arrangement for the compound formed.

(e)

Compare one physical property of compound formed (b) and (c). Explain your answer. .......... .......... ..........

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PAPER 2 : ESSAY 5 Table 5 shows the proton numbers of three elements. Element Carbon, C Sodium, Na Chlorine, Cl Table 5 (a) State the valence electron of the (i) Sodium atom (ii) Chlorine atom. [2 marks] (b) (i) Select two elements that react to form an ionic compound. State your reason. [2 marks] (ii) Referring to their proton number, explain how the compound in (b) ( i ) is formed. [6 marks] (c) (i) Select two elements that react to form a covalent compound. State your reason. [2 marks] (ii) Referring to their proton number, explain how the compound in (c )(i) is formed. [4 marks] (d) The compound in (b) has higher melting point than in (c). Explain why. [4 marks] Proton Number 6 11 17

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SET 3Electrochemistry

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Electrolysis 1. Define the meaning of electrolyte and non-electrolyte and respective examples. Electrolyte Meaning Non-electrolyte

Example

2.

Define electrolysis: .. ..

3.

Energy change :

Electrolysis: .... energy to energy. Voltaic cell: ..energy to ... energy. 4. Write the half equation to represent the discharge of anion and cation. Half equation Cation Hydrogen ion, H+ Sodium ion, Na+ Silver ion, Ag+ Half equation

Anion Hydroxide ion, OHChloride ion, ClBromide ion, BrIodide ion, IOxide ion, O2-

Lead (II)ion, Pb2+ Copper(II) ion, Cu2+ Aluminium ion, Al3+

6.

Products of electrolysis depend on three factors, they are a) ..... b) . c) .

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7.

Complete the electrochemical series below.

Cation K+ Ca2+

AnionF-

Cl-

Zn2+

H

+

Ease of discharge increases

Diagram: Electrochemical Series

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Sodium nitrate solution, 0.5 mol dm-3

Carbon electrodes

Electrolysis of sodium nitrate solution. 8. Describe the electrolysis of sodium nitrate solution using carbon electrodes. Anode Write the formula of all ions present in the electrolyte. Write the formula of ion/ions which is/are attracted to anode and cathode. Which is selectively discharged? Give a reason. Cathode

Write the half equation to represent the discharge.

What will you observe at the electrode? Name the product. State the test to identify the product.

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Potassium chloride solution, 0.5 mol dm-3 Carbon electrodes

Electrolysis of potassium chloride solution

9.

Describe the electrolysis of potassium chloride solution using carbon electrodes. Anode Cathode

Write the formula of all ions present in the electrolyte. Write the formula of ion/ions which is/are attracted to anode and cathode. Which is selectively discharged? Give a reason.


What will you observe at the electrode?

Name the product.

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Copper electrode Copper(II)nitratesolution, 0.5 mol dm-3

Iron electrode

Electrolysis of copper (II) nitrate solution 10. Describe the electrolysis of copper (II) nitrate solution using metal electrodes.

Anode Write the formula of all ions present in the electrolyte. Write the formula of ion/ions which is/are attracted to anode and cathode. Which is selectively discharged? Give a reason.

Cathode


What will you observe at the electrodes?

Name the product. What will you observe to the electrolyte? Explain why?

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Voltaic cell / Simple cell

Zinc electrode Copper(II)sulphate solution, 0.5 mol dm-3 Copper electrode

11.

Describe the voltage cell. Negative terminal State all ions present in the electrolyte. Identify positive terminal and negative terminal. Explain why? Write half equation at negative terminal. Write the formula of ions which are moved to positive terminal. Which is selectively discharged? Give a reason. Half equation at positive terminal What will you observe at negative and positive terminal? What will you observe to the electrolyte? Explain why? Overall / Full ionic equation Positive terminal

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Application of electrolysis 12. State the aim of electroplating of metal. .... .... 13. The principal of electroplating. (a) The thing to be electroplating must be ... (b) The electrolyte .... (c) The anode ... 14. To electroplate the spoon with silver.

Iron spoon

Silver electrode Silver nitrate solution, 0.5 mol dm-3

(a)

Write the half equation at silver electrode. .. Write the half equation at iron spoon. .. State the observation at silver electrode. ..

(b)

(c)

(d)

State the observation at the iron spoon. .. An even and lasting layer of metal is obtained if: .. ..

(e)

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15.

Purification of metal. (a) Things to be purified must be at ... (b) The other electrode ... (c) The electrolyte ..

The electrochemical series 16. The electrochemical series .. .. The electrochemical series can be constructed based on; (a) The potential difference between two metals, in voltaic cell. The higher the voltage value, the (b) The ability/ tendency of a metal to displace another metal from its salt solution. A metal which able to displace metal below it in the series from its salt solution.

17.

PAPER 2: STRUCTURE 1. Diagram 1 show the apparatus set-up used to electrolyze 0.1 mol dm-3 of sodium chloride solution using carbon electrodes.

Gas Q Gas P 0.1 mol dm-3 of sodium chloride solution Electrode X _ + Electrode Y

Diagram 1(a) Name electrodes X and Y. .... [1 mark]

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(b)

Write the formula of all ions present in the solution. ... [1 mark] (i) Name gas P collected in the test tube. .. [1 mark] (ii) State a chemical test to confirm your answer to (c)(i). .. [1 mark] (iii) Write a half equation for the reaction that takes place at electrode X. ... [1 mark] Name gas Q collected in the test tube.

(c)

(d)

(i)

... [1 mark] (ii) State a chemical test to confirm your answer to (d)(i). .. [1 mark] (iii) Write a half equation for the reaction that takes place at electrode Y. .. [1 mark] What difference will it make if the experiment is repeated by using 2 mol dm-3 of sodium chloride solution? Explain your answer. .. .. [2 marks] 2. Diagram 2 shows the apparatus set-up to carry out an electrolysis of aqueous copper(II) sulphate solution.

(e)

carbon electrdes Experiment I

0.2 mol dm-3 of copper(II) sulphate solution Experiment IIDiagram 2

copper elecrodes

(a)

Write the formula of all the ions present in the copper(II) sulphate solution. .. [1 mark]

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(b)

(i)

Name the product produced at the anode in Experiment I.

.. [1 mark] (ii) Write a half equation for the reaction that takes place at this electrode. .. [1 mark] (i) Name the product produced at the anode in Experiment II. .. [1 mark] (ii) Write a half equation for the reaction that takes place at this electrode. .. [1 mark] (d) (i) What happen to the intensity of the blue copper(II) sulphate solution in Experiment I? .. [1 mark] (ii) Explain your answer in (d) (i).

(c)

(e)

.. [1 mark] (i) What happen to the intensity of the blue copper(II) sulphate solution in Experiment II? .. [1 mark] (ii) Explain your answer in (e) (i). .. .. [1 mark]

3.

Diagram 3 shows a simple cell

V

electrode X

electrode Y electrolyteDiagram 3

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Two different electrodes are immersed into an electrolyte. The voltage of the cell is recorded. The experiment is repeated by using different pairs of electrode. Table 3 shows the results obtained. The metals of which electrodes V, W, X, Y and Z are made of, for divalent ions. Experiment 1 2 3 4 Pairs of electrodes X/Y X/Z X/W Y/V Positive terminal Y X X V Table 3 Negative terminal X Z W Y Voltage/V 0.70 1.05 1.55 0.50

(a)

Suggest a suitable electrolyte for the above experiments. ... [1 mark] State the direction of the flow of electrons in Experiment 1 which used electrodes X and Y. .... [1 mark] Write half equation for the reaction that takes place at the negative terminal in Experiment 2 which used electrodes X and Z. .... [1 mark] State a hypothesis for the above experiments.

(b)

(c)

(d)

.. [1 mark] (e) Arrange the metals V, W, X, Y and Z in decreasing order in the Electrochemistry Series. .... [1 mark] A chemical cell is set-up using electrodes Z and V. (i) State the negative terminal of the cell. ... [1 mark] (ii) Calculate the voltage of the cell.

(f)

[1 mark] (g) (i) State the pair of electrodes that will give the highest voltage reading.

.. [1 mark] (ii) Calculate the voltage of the cell.

[1 mark]

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PAPER 2 : ESSAY 4. (a) Ethanoic acid solution is electrolysed by using platinum electrode. What is produced at the cathode? Write a half equation for the reaction that occurs at the cathode. [2 marks] (b) Diagram 4 shows Cell X and Cell Y.

V

Zinc plate

Copper plate copper(II) nitrate Cell XDiagram 4

copper electrode

Cell Y

Cell X is a chemical cell while cell Y is an electrolytic cell. Compare cell X and cell Y. [8 marks] (c) A student wants to purify an impure copper plate by the process of electrolysis. Design an experiment in the laboratory to purify the impure copper plate. Your answer should include the following: materials and apparatus needed a diagram with the arrangement of apparatus the procedure observation chemical equation involved [10 marks] PAPER 3 : STRUCTURE 5. A student carries out an experiment to study the potential difference between two types of different metals. The apparatus arrangement used is shown in Diagram 5.

Before experiment V

After experiment V

zinc plate

Zinc plate iron plate copper(II) nitrate Diagram 5

iron plate

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(a)

State the observation and inference involved in the experiment in the table below. Metal plate Zinc Iron Observation Inference

(b)

The student repeated the experiment by replacing the iron metal with copper metal, aluminium metal and magnesium metal. Table 5 shows the voltage reading obtained from the metal pairs. Metal pairs Zinc iron Zinc copper Zinc almunium Zinc magnesium Negative terminal Zinc Zinc Aluminium Magnesium Table 5 Positive terminal Iron Copper Zinc Zinc Voltage/V 0.4 1.1 0.8 1.4

Based on the information above, complete the table below. Type of variables (i) Manipulated variables : ___________________________ (ii) Responding variables : ___________________________ (iii) Constant variables : ___________________________ Action to be taken (i) Way to change the manipulated variables : _________________________________ (ii) How do these variables respond: _________________________________ (iii) Way to fix the constant variables : _________________________________

[6 marks] (c) State the hypothesis of the experiment .. (d) If the experiment is repeated by using lead metal to replace iron metal, predict the possible reading recorded by the voltmeter. ..

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6. Diagram 6 shows two set-up apparatus used to electrolyzed 0.001 mol dm-3 hydrochloric acid and 1.0 mol dm-3 hydrochloric acid by using carbon electrodes.

Carbon electrode

0.001 mol dm-3 hydrochloric

1.0 mol dm-3 hydrochloric

acidDiagram 6 (a) State a suitable hypothesis for the experiment.

acid

.. (b) State all the variables involved in the experiment (i) Manipulated variable .. (ii) Responding variable .. (iii) Constant variables .. (c) Write the observations at the anode and cathode for both sets of experiment. Electrolyte Terminal Anode Set 1 ( 0.001 mol dm-3 hydrochloric acid ) Set 2 ( 1.0 mol dm-3 hydrochloric acid )

Cathode

(d)

Write half-equation for the discharge of ions at anode for Set 1 and Set 2. .. .....

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(e)

Predict the observation at the anode and cathode when 0.0001 mol dm-3 potassium nitrate solution is electrolysed. .. ..

PAPER 3 : ESSAY 7. Concentration of ions used during electrolysis affects the product of electrolysis at the anode. Using sodium chloride solution, describe an experiment to prove the above statement. Your answer should include: (a) (b) (c) (d) (e) (f) Problem statement Hypothesis Variables Materials and apparatus used Procedure of the experiment Tabulation of data

The further the distance between two metals in the electrochemical series, the bigger the potential difference .8. You are given the copper strip, lead strip, iron strip, zinc strip, aluminium strip, magnesium strip and copper(II) sulphate solution.Referring to the statement above, plan a laboratory experiment to construct the electrochemical series of the potential differences using different pair of metals. Your explanation should include all the followings: (a) (b) (c ) (d) (e) (f) Aim of the experment All the variables Statement of the hypothesis List of materials and apparatus Procedure of the experiment Tabulation of data [ 17 marks ]

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SET 4Acids and Base Salts

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ACID AND BASES 1. An acid is a chemical compound that produce hydrogen ion, H+ or hydroxonium, H3 O+ when dissolves in water. HCl + H2O H3O+ + ClH2O HCl H+ + Cl-

2. 3.

An acid shows its acidic properties only in the presence of water. A base is defines as a chemical substance that can neutralise an acid to produce a salt and water. Example: CuO + 2HCl CuCl2 + H2O

4.

An alkali is defined as a chemical compound that dissolves in water to produce hydroxide ions, OH-. Example: HO2

KOH 5. Define weak acid :

K+ + OH-

.................................. 6. Define strong acid : .................................. 7. Define strong alkali : .................................. 8. Define weak alkali: .................................. 9. Define basicity : the number of ionisable ....................................................... of an acid. Using a suitable examples explain what is meant by a) Monoprotic acid : ............................... b) Diprotic acid : ............................... c) Triprotic acid : ............................... atoms per molecule

10.

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11.

Write an equation of dissociation for the following acid. a) Nitric acid : ............................... b) Ethanoic acid : ............................... c) Carbonic acid : ............................... d) Sulphuric acid : ............................... e) Chemical properties of acid. Reaction With reactive metal Product Salt and hydrogen gas Example and Chemical equation Zn + 2HCl ZnCl2 + H2

PAPER 2 : STRUCTURE 1. An experiment is carried out in the laboratory to determine the end point of the reaction between 25.0 cm3 of potassium hydroxide solution and 1.0 moldm-3 of sulphuric acid. Phenolphthalein is used in the titration to detect the end point of the reaction. diagram 1 shows the set-up of apparatus for the titration.

Sulphuric acid 1.0 moldm-3

Potassium hydroxide + phenolphthalein

Diagram 1

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The volume of sulphuric acid added and the change of the colour of potassium hydroxide solution shown in the Table 1 below. Volume of sulphuric acid (cm3) Colour of potassium hydroxide solution

4,5

4.6

4.7 Pink

4.8

4.9

5.0

5.1

5.2

5.3

Colourless

Table 1(a) Name the chemical reaction between potassium hydroxide solution and sulphuric acid. .................. [1 mark] (b) Write a chemical equation for the reaction. ................. (c) [1 mark] Write the formula of ions which are present in the conical flask when the volume of sulphuric acid added is: (i) 4.5 cm3 ................................................................................................................................... (ii) 5.0 cm3 ................................................................................................................................... [2 marks] (d) What is the volume of sulphuric acid needed to neutralise 25 cm3 potassium hydroxide solution? ..................................................................................................................................... [1 mark] (e) Calculate the concentration of potassium hydroxide solution in this experiment.

(f)

[2 marks] If sulphuric acid is replaced with nitric acid with the same molarity, predict the volume of nitric acid require to neutralise 25.0 cm3 of the potassium hydroxide solution. Explain why. .................................................................................................................................... .................................................................................................................................... [2 marks]

2.

Hydrogen chloride gas is dissolved in two different solvent, producing solutions X and Y.

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Experiment I and II are carried out. Table 2 below shows the results of the experiment. Observations Experiment Solution X I II Marble chips added into solutions Electrical conductivity Gas bubbles Deflection of ammeter reading Solution Y No changes No deflection of ammeter reading

Table 2a) Name a suitable solvent to produce (i) Solution X ..................................................................................................................................... Solution Y ..................................................................................................................................... [2 marks] b) (i) Which solution shows acidic properties ................................................................................................................................. What is the role of the solvent used to produce the acid in (b)(i) ................................................................................................................................. ................................................................................................................................. [2 marks] c) (i) Name the gas produce in Experiment I ................................................................................................................................ Describe a chemical test to verify the gas in (c)(i). ................................................................................................................................. ................................................................................................................................ [3 marks] d) Solution X can conduct electricity but solution Y cannot. Explain this statement. .......................................................................................................................................... .......................................................................................................................................... [2 marks]

(ii)

(ii)

(ii)

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3.

Table 3, below shows the pH value of four solutions. The solutions are of the same concentration Solution pH W 1 X 5 Y 7 Z 14

Table 3a) (i) Name one example of solution Z.

................................................................................................................................. (ii) Write a chemical equation for the reaction of Z in a(i) with sulphuric acid. ................................................................................................................................. (iii) Name the chemical reaction occur in a(ii). ................................................................................................................................. [3 marks] b) Which solution possibly can be sodium sulphate? .......................................................................................................................................... [1 mark] c) (i) Which solution can change a blue litmus paper to red? ................................................................................................................................. State one test to prove the chemical property of c(i) without using an indicator. ................................................................................................................................. ................................................................................................................................. .

(ii)

[3 marks] d) Explain why solution W and Solution and solution X have different pH values. ..................................................................................................................................... ..................................................................................................................................... [2 marks]

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Dry hydrogen chloride gas

Filter funnel

Methyl benzene `

Beaker ADry hydrogen chloride gas Filter funnel Water

Beaker B4. Figure above shows the arrangement of apparatus used to prepare hydrogen chloride in methyl benzene and in water respectively. a) What is the purpose of using filter funnels in this experiment ? ................................................................................................................................................ [1 mark] b) (i) What is observed when a piece of magnesium ribbon is placed in Beaker A and Beaker B respectively. Beaker A : ................................................................................................................. Beaker B :................................................................................................................. State the reason for your answer in b(i) ................................................................................................................................... ................................................................................................................................. [3 marks] c) Name the types of particles present in Beaker A ; ........................................................................................................................ Beaker B : ........................................................................................................................ [2 marks]

(ii)

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d) Water is added to the solution in Beaker A and the mixture is then shaken. When sodium carbonate solution is added, effervesence occurs. (i) Name the gas and suggest a suitable test to identify the gas evolved. ................................................................................................................................ State the role of water that caused the liberation of the gas. ................................................................................................................................. Write the ionic equation for the reaction involving the liberation of the gas. .................................................................................................................................. [3 marks]

(ii)

(iii)

5.

Diagram 5 shows four test tubes contain dry glacial ethanoic acid, aqueous solution of dilute hydrochloric acid and aqueous solution of X.

ethanoic acid,

Dry glacial ethanoic acidBlue litmus paper P

Aqueous solution of ethanoic acid 0.1 moldm-3 Blue litmus paper Q

Dilute hydrochloric acid Blue litmus paper R

Aqueous solution of X

S

Diagram 5a) (i) State the colour change of the litmus paper in test tubes Q and R. ................................................................................................................................ (ii) Write the formula of ion which caused the colour change of the litmus paper. ..................................................................................................................................... [2 marks] b) Is there any changes of colour of the litmus paper in test tube P? Explain why. .............................................................................................................................................. .............................................................................................................................................. [2 marks]

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c)

Table 5 shows the pH value of aqueous solution of ethanoic acid and of the same molarity. Type of acid Molarity pH value aqueous solution of ethanoic acid 0.1 moldm-3 3.0

dilute hydrochloric acid

dilute hydrochloric acid 0.1 moldm-3 1.0

Table 5Explain why the pH value of aqueous solution of ethanoic acid is higher than the pH value of dilute hydrochloric acid. .............................................................................................................................................. .............................................................................................................................................. .............................................................................................................................................. d) [2 marks] Calcium carbonate powder is added into test tube R. Write the chemical equation for the reaction that takes place. .................................................................................................................................................. [1 mark] e) Aqueous solution of X is an acidic solution. As a chemistry student, describe briefly how you are able to prove that X is an acidic solution. You are not allow to use litmus paper, pH meter or any indicators. Procedure:

.................................................................................................................................................. ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... [3 marks] Observation:

................................................................................................................................................... .................................................................................................................................................. [1 mark]

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6.

(a)

A student carried out an experiment to study the pH of a few aqueous solutions using pH The results were tabulated below. Aqueous solution pH P 13 Q 7 R 4 S 8 T 20 U 1

paper.

Table 6Which of the solution in the table above could be (i) Distilled water . Vinegar . (iii) Sodium hydroxide ..... (iv) Hydrochloric acid ..... [4 marks] b) (i) An apple contains maleic acid C4H8O5 which is a weak acid, What is meant by weak acid ? . (ii) The pH of 1.0 mol dm-3 maleic acid solution is higher than hydrochloric acid with the same concentration. Explain why. ..... . [2 marks] c) Zinc powder is added to the test tube containing hydrochloric acid. (i) Name the gas released. . (ii) Describe a chemical test to identify the gas. . . (iii) Write a balanced equation for the reaction. . [3 marks]

(ii)

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PAPER 2: ESSAY 7. (a) (i) (ii) What is meant by standard solution ?,

(b)

[1 mark] Describe how 100cm3 of 2.0 moldm-3 sodium hydroxide solution can be prepared in the school laboratory, Your description should include the calculation Use the information, Relative atomic mass of Na = 23, O =16 , H = 1 [7 marks] -3 Using the 1.0 mol dm sodium hydroxide solution from (a) above. Describe how you would determine the unknown concentration of a sample of hydrochloric acid, HCl using the titration method. You may use either methyl orange or phenolphthalein as indicator. Include, in your answer, the chemical equation and calculation. [12 marks]

8.

(a)

The following information is about sodium hydroxide solution and ammonia solution. pH of sodium hydroxide solution 1.0 mol dm-3 is 14 pH of ammonia solution 1.0 mol dm-3 is 10 Explain why both solutions have different pH value. [6 marks]

(b)

The label of a reagent bottle was dirty caused by a chemical substance. The reagent is suspected to contain dilute hydrochloric acid. Describe two chemical tests which can be used to identify the chemical chemical solution is dilute hydrochloric acid. solution if the [8 marks]

(c)

Glacial ethanoic acid does not release any gas when it is poured into pieces of calcium carbonate. However, effervescence occurs when several drops of water are added into the mixture of ethanoic acid and pieces of calcium carbonate. Explain the statement. [ 6 marks]

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PAPER 3: STRUCTURE 9. Diagram 9 shows the results of titration between sulphuric acid and sodium hydroxide solution.

1.0 mol dm-3 Sulphuric acid, H2 SO4

Initial reading

Final reading

25.0 cm3 sodium hydroxide, NaOH solution + phenolphthalein DIAGRAM 9 (a) Based on the diagram 2, record the final and initial burette readings of the burette.

Final reading Initial reading Volume of H2SO4 used

= = =

. cm3 . cm3 cm3 [3 marks]

(b)

Construct a table that can be used to record the result of the experiment.

[3 marks]

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(c)

(i)

State the colour change in the solution. [3 marks] State the inference of the colour change.

(ii)

(d)

. [3 marks] Write the operational definition for the neutralisation. [3 marks]

(e)

You are given three examples of acids; sulphuric acid, ethanoic acid and hydrochloric acid. Classify them into monoprotic and diprotic acids.

[3 marks] (f) Based on the titration results, calculate the molarity of sodium hydroxide solution used . Given the chemical equation for the neutralisation is as follow: 2NaOH + H2SO4 Na2SO4 + 2H2O

[3 marks]

10.

A student carried out two experiments to determine the concentration of HX acid solution. Experiment I Titration of HX acid solution of unknown concentration with 20cm3 of sodium hydroxide solution 1.0 mol dm-3 using phenolftalein as indicator. Experiment II Titration of similar HX acid solution of difference concentration with 20cm3 of sodium hydroxide solution 1.0 mol dm-3 using phenolftalein as indicator.

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Diagram 10, shows the initial and final burette readings for both experiments. Experiment 1

0

20

1

21

Initial burette reading Experiment II

Final burette reading

15

25

16

26

Initial burette reading Diagram 10

Final burette reading

(a)

Construct a table to record the initial and final burette readings and the volumes of the acid used for both experiments.

[ 3 marks] (b) State the colour change of phenolftalein in the titration. ................... [ 3 marks]

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(c)

The chemical equation for the reaction in the experiment is : HX + NaOH NaX + H2O

Calculate the concentration of HX acid solutions used in both experiments. (i) Experiment I

(ii)

Experiment II

[ 3 marks] (d) State the hypothesis in this experiment. ............... ....... [ 3 marks] (e) If HX acid is replaced with sulphuric acid of the same concentration, it is found that the volume of the sulphuric acid used in the titration is half of the volume of HX acid. Explain why. ....... ....... ....... [ 3 marks] PAPER 3 : ESSAY 11. Solid sodium hydroxide does not give any effect on dry red litmus paper. On the other hand, sodium hydroxide solution changes dry red litmus paper to blue.

With reference to the above statement, plan an experiment in the laboratory to study the role of water on the properties of alkali. Your planning of experiment must include the following: a) Problem statement b) Hypothesis c) List of materials and apparatus d) Procedure e) Tabulation of data

[17 marks]

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SALTS 1. A salt is an ionic compound that is formed when the ion in

an acid is replaced by a ion or ammonium ion (NH4+). 2. Solubility of salts. Type of salt Sodium, potassium and ammonium salts Nitrate salts Sulphate salts Chloride salts Carbonate salts Solubility in water All are soluble.

3.

Preparation of soluble salts. Preparation of soluble salts An acid reacts with reactive metal. Example / Reactants Magnesium and hydrochloric acid Chemical equation Mg + 2HCl MgCl2 + H2

4.

Insoluble salts can be prepared by .. in double decomposition reaction. Example: Silver nitrate solution reacts with sodium chloride solution, white precipitate formed. Chemical equation: Ionic equation : AgNO3 + NaCl AgCl(s) + NaNO3

Ag+ + Cl- AgCl(s)

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5.

Quantitive analysis of salts. (a) Colour of salts Colour White or colourless Green Solid Sodium,potassium,magnesium, ammonium, Lead ,chlorides, sulphates,nitrates. Solution Na+,K+,Mg2+, Pb2+, Zn2+, NH4+

Blue

Brown

(b)

Action of heat on Carbonate and Nitrate salts. Type of salt Colour of salt before heating Hot Copper (II) carbonate Lead (II) carbonate Lead (II) carbonate Zinc carbonate Magnesium nitrate Zinc nitrate Sodium nitrate White Brown Colour of residue Cold

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(c)

Test for Anions.

Summarise the tests used to identify anions in the table below. Anion Carbonate, CO32Chloride, ClSulphate, SO4 2Nitrate, NO3White precipitate is formed, sulphate ion is present. Test Add 2 cm3 hydrochloric acid, bubble the gas produced through lime water. Observation and inference

(d)

Specific tests for cations Reagent Observation

Cation Ammonium, NH4+

Iron (II), Fe2+

Iron (III), Fe3+

Lead (II), Pb2+

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PAPER 2: STRUCTURE

Oxide M (Brown when hot, yellow when cooled)Heat

Compound J

+ Gas L (Colourless)

+ dilute nitric acid asid nitrik cair

White precipitate Q

Reaction I

(Dissolved in excess sodium hydroxide + NaOH (aq) solution)

Colourless J solution

Reaction II

White precipitate R+ H2SO4 (aq)

Diagram 11. Diagram 1 shows a series of chemical test done by a student to identify a compound J. a) With reference to reaction I, white precipitate Q is formed when reacts with sodium hydroxide solution and it is soluble in excess sodium hydroxide solution. Name all the ions which are probably present in solution J. .............................................................................................................................................................. [1 mark] Referring to reaction I and II, Name the cation that is present in solution J. .............................................................................................................................................................. [1 mark] Write the ionic equation for the reaction forming the white precipitate, R. . [1 mark] d) Name two cations which produce white precipitates with sodium hydroxide solution that do not dissolve in excess sodium hydroxide solution. .... [1 mark]

b)

c)

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(e)

Describe a confirmatory test which you can use to differentiate the cations you named in (d). ........................................................................................................................................................... ........................................................................................................................................................... ........................................................................................................................................................... ........................................................................................................................................................... [4 marks]

2.

An experiment to investigate the effect of heat on solid lead (II) carbonate is shown on diagram 2. Boiling tube

Lead (II) carbonate

Heat Lime water

Diagram 2(a) (i) State two observations of the above experiment. [2 marks] (ii) Write an equation for the reaction .. [1 mark] (iii) Name the residue formed inside the boiling tube at the end of the experiment ..... [1 mark]

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(b)

The result of the experiment is shown in Table 2. [Relative atomic mass: Pb=207, C=12, O=16; 1 mol of gas occupies 24dm3 at room temperature and pressure] Substance Mass of boiling tube Mass of boiling tube and lead (II) carbonate before heating Mass of boiling tube and residue after heating Mass (g) 12.45 23.13 22.56

Table 2(i) Calculate the mass lead (II) carbonate used.

[2 marks] (ii) Calculate the mass of residue formed.

[2 marks] (iii) Calculate the volume of carbon dioxide evolved at room temperature and pressure.

[2 marks] (c) All the residue is formed during the heating of lead (II) carbonate was dissolved in dilute nitric acid to form a colourless solution. When excess of sulphuric acid is added to the colourless solution, a white precipitate is formed. (i) Name the white precipitate formed. .. [1 mark] Write an ionic equation for the reaction. .. [1 mark]

(ii)

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3.

Diagram 3 shows the formation of zinc nitrate and its conversion to other substances+ dilute nitric acid

W nitrate+ dilute NaOH (aq)

Zinc nitrate

Nitrogen dioxide + Gas X

+ potassium iodide solution

+ sodium carbonate solution

Y + sodium nitrate R + sodium nitrate Z + potassium nitrate Diagram 3(a) W is a white powder which reacts with dilute nitric acid. The powder is yellow in hot. Give the name of W. [1 mark] A small amount of sodium hydroxide solution is added to zinc nitrate solution. Precipitate Y is produced. (i) Write the chemical formula of Y. .. [1 mark] Describe what happens when sodium hydroxide is added to zinc nitrate. .. [1 mark] Zinc nitrate can be converted to nitrogen dioxide and gas X. How can this conversion be carried out? .. [1 mark] Name gas X .. [ 1 mark] (iii) Describe the observation during the experiment. .. .. [1 mark]

(b)

(ii)

(c)

(i)

(ii)

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(d)

When potassium iodide is added to zinc nitrate solution a precipitation takes place. (i) Name the substance Z .. [1 mark] Write an ionic equation to show how Z is produced.

(ii)

(e)

.. [1 mark] Write the chemical formula of substance R .. [1 mark]

PAPER 2: ESSAY 4. (a) The following are three examples of sulphate salts that can be prepared in the laboratory. Potassium sulphate Lead (II) sulphate Zinc sulphate (i) From these examples, identify soluble and insoluble salts [2 marks] (ii) State the reactants for the preparation of the insoluble salts in 4 (a) (i). [2 marks]

(b)

With the aid of a labeled diagram, explain the crystallization method for preparing a soluble salt from its saturated solution. [6 marks]

(c)

You are given a solution that contains a mixture of iron (III) nitrate and iron (III) chloride. Describe the confirmatory test to determine the presence of cation and anion in the solution. Your description must include all the materials used, observation and conclusion. [10 marks]

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5. (a)

Lead (II) sulphate is insoluble in water. Describe the preparation of lead (II) sulphate in the laboratory. In your description, include the reagents and chemical equation involved. [10 marks]

(b)

Table 5 shows the observations from some tests carried out on salt X. Test I: Heating on salt X solid II: Salt X solution is mixed with excess aqueous ammonia Observation A metal oxide is formed and a brown gas is given off. A white precipitate which is insoluble in excess ammonia is formed.

Table 5Based on the information in Table 5. (i) Identify anion that is present in Test I and describe a chemical test to verify the anion. [4 marks] Identify two cations that are present in Test II and describe a chemical test to verify the cations. [6 marks]

(ii)

PAPER 3: STRUCTURE 6. Seven test tubes of the same size are labelled 1 to 7. A fixed volume of 5.0 cm3 of 1.0 moldm-3 potassium chromate (VI) solution is placed in each of the seven test tubes. Varying amounts of 1.0 moldm-3 of a nitrate salt of metal M is added to each test tube. For example, 1 cm3 to test tube 1, 2 cm3 of test tube 2, and so on until 7 cm3 is added to test tube 7. The height of the yellow precipitate formed in each test tube are recorded in the table 6. Test tube Height of precipitate (cm) 1 1.0 Table 6 2 2.0 3 3.0 4 4.0 5 5.0 6 5.0 7 5.0

(a)

Based on results from table 6 , plot a graph of precipitate heights against volumes of M nitrate solution added.

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(b)

What is the volume of M nitrate solution that reacted completely with 5.0 cm3 of potassium chromate (VI) solution? Explain your answer. .

(c)

Calculate the number of moles of potassium chromate (VI) found in the test tube and the number of moles of M ions that reacted completely with the 5.0 cm3 of potassium chromate (VI) solution.

(d)

Determine the formula of M chromate (VI). ...

(e)

Write the ionic equation for the formation of M chromate (VI). .. [1 mark]

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7.

Diagram shows two containers, containing colourless solution labelled A and B.

A

B

You are told that the two colourless solutions are calcium nitrate and magnesium nitrate. You are required to label correctly the name of each solution in the containers. Design an experiment to identify which is calcium nitrate and which is magnesium nitrate solution by using aqueous of ammonia solution as a reagent. Your answer should include the following: (a) Problem statement (b) Hypothesis (c) All variables (d) List of materials and apparatus (e) Procedure (f) Tabulation of data [17 marks]

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SET 5Manufactured Substances in Industry

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PAPER 2 : SRUCTURE 1 Ammonia is produced in mass quantities in industry through a process as shown in diagram 1 below. Nitrogen Gas

Catalyst chamber

Ammonia gas

Hydrogen gas

Diagram 1(a) State the name of the process for the production of ammonia in industry. ............................................................................................................................................................... [1 mark] Write an equation for the process stated in (a)? .............................................................................................................................................................. [1 mark] State the catalyt used in this process? ............................................................................................................................................................... [1 mark] Other than the use of catalyst, state two conditions required for optimum production of ammonia. ............................................................................................................................................................... [1 mark] Ammonia react with sulphuric acid to form a fertilizer.Name the fertilizer. ............................................................................................................................................................... [1 mark] The reaction between ammonia and carbon dioxide produce urea, CO(NH2)2 and water. (i) Write the equation for the reaction. ...................................................................................................................................................... [1 mark] Determine the percentage by mass of nitrogen in urea. [Relative atomic mass ; H,1; C,12; N,14; O,16 ]

(b)

(c)

(d)

(e)

(f)

(ii)

(g)

[2 marks] Aqueous ammonia can be used as a reagent to identify cations. State the observation when aqueous ammonia is slowly added until excess to a solution containing Cu2+ ion. ................................................................................................................................................................ ............................................................................................................................................................... [2 marks]

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2.

Diagram 2 shows a flow chart for the formation of Salt A through Process X and Process Y.

Sulphur Nitrogen

Sulphur dioxide

Process X

Sulphur trioxide

Hydrogen

Process Y

Ammonia

Sulphuric Acid

Salt ADiagram 2 (a) Name (i) (ii) Process X : .................................................................................................... Process Y : .................................................................................................... [2 marks ] (b) (i) Write the equation for the formation of sulphur trioxide in Process X .................................................................................................................................................... [1 mark] State the catalyst used in Process X ................................................................................................................................................... [1 mark ] (c) (i) Write the equation for the formation of ammonia in Process Y ..........................................................................................................................

Chemistry Perfect Score Module Form 4 2011 No Logo

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