1.  How much energy is required to heat 5.00 g water from 4°C to 37°C? (ΔH° fus = 6.01 kJ/mol; ΔH° vap = 40.76 kJ/mol; c = 75.3 J/mol • °C)

a) 12425 J

b)

691 J

c) 75.3 J

d)

376.5 J

The heat required, q = ncΔT. n = number of 

moles = 5.00 g × = 0.278 mol. c = heat capacity of water = 75.3 J/mol , ΔT = 37 - 4 = 33°C. Therefore,q = (0.278 mol)(75.3 J/mol • °C)(33°C) = 691 J.

2.  Which of the following is a formation reaction?

a) K+(g) + Br-(g) → KBr(s)

b)

2 K(s) + Br2(g) → 2 KBr(s)

c) K(g) + Br(g) → KBr(s)

d)

none of the above

Sorry, but the correct answer is (d).A formation reaction is the formation of 1 mole of substance from its elements at standard state. 

Therefore, the correct answer is K(s) +  Br2(ℓ) → KBr(s).

3.  The ΔH°f of Ar(g) is

a) positive

b)

negative

c) zero

d)

must be determined experimentally

Sorry, but the correct answer is (c).Argon gas is an element in its standard state; therefore, its enthalpy of formation is zero.

4.  Experimental determination of energy is called

a) work

b)

enthalpy

c) calorimetry

d)

Hess’s law

5. Boiling water is   a)exothermic and increasing in temperature 

b)endothermic and increasing in temperature  c)exothermic and constant

temperature  d)endothermic and constant temperature

6.  If a reaction has a ΔH = +369 kJ/mol, the ΔH of the reverse reaction is

a) +369 kJ/mol

b)

-369 kJ/mol

c) +185 kJ/mol

d)

-185 kJ/mol

7.  Which of the following is a state function?

a) ETA (estimated time of arrival)

b)

mileage

c) altitude

d)

all are state functions

8.  Which element is not in its standard state?

a) H2(g)

b)

Na(s)

c) Ne(g)

d)

Cl(g)

9.  The heat capacity of a calorimeter is 2.22 kJ/°C. What is the temperature change if 997 J of energy is absorbed by a reaction in that calorimeter?

a) 2.21°C higher

b)

2.21°C lower

c) 0.449°C higher

d)

0.449°C lower

Sorry, but the correct answer is (d).

997 J × ×  = 0.449°C. Because energy is absorbed, the temperature will decrease.

10.  A product of a combustion reaction is

a) gaseous water

b)

hydrocarbon

c) saturated hydrocarbon

d)

all of the above

11.  The heat capacity of aluminum is 25.4 J/mol • °C. How much energy is released when 5.00 g Al is cooled from 50°C to 30°C?

a) 2440 J

b)

90 J

c) 488 J

d)

3.7 J

Correct!

q = ncΔT, so 5.00 g Al ×  = 0.185 mol; c = heat capacity = 24.4 J/mol • °C; ΔT = 50 - 30 = 20. Therefore, q = (0.185)(24.4)(20) = 90 J.

12.  What is the heat capacity of a bomb calorimeter if the combustion of 0.3550 g of benzoic acid (ΔH° = -26.38 kJ/g) raises the temperature of the calorimeter from 25.13°C to 33.30°C?

a) 9.40 J/°C

b)

1.15 kJ/°C

c) 1.149 J/°C

d)

23.0°C

Sorry, but the correct answer is (b).

Heat capacity = q/ΔT. q = 0.3550 g × = 9.365 kJ. ΔT = 8.17°C. So heat capacity = 

= 1.15 kJ/°C.

13.  How much energy is required to melt 10.0 g of water at 0°C? (ΔH° fus = 6.01 kJ/mol; ΔH° vap = 40.76 kJ/mol ; c = 75.3 kJ/mol • °C)

a) none

b)

6.01 J

c) 60.1 kJ

d)

3.33 kJ

The heat of fusion is 601 kJ/mol for water. 

10.0 g H2O × = 0.555 mol, so to melt 10.0 g water, (0.555 mol)(601 kJ/mol) = 3.33 kJ.

14.  The specific heat of water is

a) 75.3 J/mol • °C

b)

23.38 J/mol • °C

c) 4.18 J/g • °C

d)

601 kJ/mol

Top of Form15.  How much work is done when a balloon is inflated to 1.00 L at 760 torr?

a) 101 J

b)

1.00 J

c) 760 J

d)

7.60 J

Bottom of Form

Sorry, but the correct answer is (a).Work at constant pressure = PΔV. Since 760 torr is 1 atm and the change in volume is from 0 to 1.0 L, the work done is 1.0 L • atm. Using the conversion factor 101.32 J = 1 L • atm, inflating the balloon requires 101 J of work.

16.  The reaction K + Cl2 + 2 O2→ KClO4 has a ΔH = -432 kJ/mol. What is the ΔH of 2 KClO4 → 2 K + Cl2 + 4 O2?

a) -432 kJ/mol

b)

+432 kJ/mol

c) -216 kJ/mol

d)

+864 kJ/mol

Sorry, but the correct answer is (d).The equation was reversed and multiplied by a factor of 2. Therefore, the sign on ΔH changes and its value is multiplied by two.

17.  If 5.0 kJ is gained by the surroundings, then

a) the system lost 5.0 kJ

b)

the system gained 5.0 kJ

c) the system gained 10 kJ

d)

the system gained 12 kJ

18.  Which will have the greater temperature change if the same amount of energy is applied to 1 mole of each of the following?

a) iron (c = 25.19 J/mol • °C)

b)

gold (c = 25.41 J/mol • °C)

c) magnesium (c = 24.79 J/mol • °C)

d)

platinum (c = 25.95 J/mol • °C)

19.  The energy of melting is called

a) the heat of fission

b)

the heat of liquefication

c) the heat of vaporization

d)

the heat of fusion

20.  The first law of thermodynamics is

a) heat lost equals heat gained

b)

energy is neither created nor destroyed

c) conservation of energy

d)

all of the above

21. Which requires more work on a 1 lb object?   a)to move it 1 ft to the

right  b)to move it up 1 ft  c)to move it down 1 ft  d)all require the same amount of work

22.  What is the heat capacity of a calorimeter if the combustion of 5.00 g of benzoic acid causes a temperature change of 14.2°C? (ΔHcombustion = -26.38 kJ/g)

a) 1070 J/°C

b)

297 J/°C

c) 1.85 kJ/°C

d)

9.29 kJ/°C

Sorry, but the correct answer is (d).The combustion of 1.00 g benzoic acid generates 26.38 kJ of heat. Therefore, 5.00 g × (26.38 kJ/g) = 131.9 kJ raises the temperature of the calorimeter 

14.2°C. The heat capacity =  = 9.29

23.  How much energy is needed to turn 10.0 g of water at 25°C to steam? (ΔH° fus = 6.01 kJ/mol; ΔH° vap = 40.76 kJ/mol; c = 75.3 J/mol • °C)

a) 3.13 kJ

b)

22.62 kJ

c) 25.75 kJ

d)

19.5 kJ

Sorry, but the correct answer is (c).To turn the water to steam, first energy must be used to raise the temperature to the boiling point of water, 100°C. Next, energy must be used to turn the water to steam. The energy required to raise the temperature from 25°C to 100°C is q = ncΔT. 

n = moles of water = 10.0 g ×  = 0.555 mol; c = 75.3 J/mol • °C; ΔT = 100 - 25 = 75°C, so (0.555)(75.3)(75) = 3134 J. The energy required to turn the water to steam (gas) is the heat of vaporization (40.76 kJ/mol). Thus for 0.555 mol it is (0.555 mol)(40.76 kJ/mol) = 22.62 kJ. To add to the energy used to raise the temperature, the units must be the same. 22.62 kJ = 22620 J. The total energy required is 22,620 J + 3134 J = 25,754 J = 25.75 kJ.

24.  Which will have the smallest temperature change for a given addition of energy?

a) 5.00 g water (c = 75.3 J/mol • °C)

b)

10.00 g water (c = 75.3 J/mol • °C)

c) 5.00 g gold (c = 25.4 J/mol • °C)

d)

10.00 g gold (c = 25.4 J/mol • °C)

Correct!

. So a smaller temperature change will occur with a higher number of moles and higher heat capacity. Since gold has a higher molar mass than water, there are fewer moles of gold than water. Gold also has a lower heat capacity. Both factors will

make gold increase in temperature more than water. The higher mass (therefore, higher number of moles) will have a smaller temperature change.

25. Which change will lead to the highest increase in kinetic energy?  

a)doubling the mass  b)doubling the velocity  c)doubling the altitude d)all these would have the same effect