SKKU Physical Pharmacy Laboratory 성균관대학교 물리약학연구실

Chapter 5.Solutions of Nonelectrolytes

SKKU Physical Pharmacy Laboratory 성균관대학교 물리약학연구실

Contents

Introductions Concentration expressions Equivalent weights Ideal solution & Real solution Colligative properties

SKKU Physical Pharmacy Laboratory 성균관대학교 물리약학연구실

Solution

Composition Solvent Solute Classification True solution ex) sucrose soln., air Coarse dispersion ex) spray, blood Colloidal dispersion ex) acacia soln.,

milk

SKKU Physical Pharmacy Laboratory 성균관대학교 물리약학연구실

Properties of Solutions

Colligative properties vapor pressure lowering, freezing point depression Additive properties molecular weight Constitutive properties refraction of light, electric properties

SKKU Physical Pharmacy Laboratory 성균관대학교 물리약학연구실

Concentration Expressions

Expression Symbol

Molarity

Normality

Molality

Mole fration

Mole percent

Percent

M, c

N

m

X, N

% w/w, v/v, w/v

CharacteristicsDependent on temp.

Dependent on temp.

Independent on temp.

SKKU Physical Pharmacy Laboratory 성균관대학교 물리약학연구실

Equivalent Weights

• Equivalent weight is …. The quantities of atom or molecule

combining with 1.008 g of hydrogen

• Equivalent weight = atomic weight / valence

SKKU Physical Pharmacy Laboratory 성균관대학교 물리약학연구실

Ideal Solution

NaCl0.01mole

1 L

“ 분자간의 인력이 균일”

SKKU Physical Pharmacy Laboratory 성균관대학교 물리약학연구실

Escaping Tendency

Temperature, Concentration, Pressure…..

SKKU Physical Pharmacy Laboratory 성균관대학교 물리약학연구실

Vapor Pressure

Equilibriumvapor pressure

SKKU Physical Pharmacy Laboratory 성균관대학교 물리약학연구실

Raoult’s Law

PA= P’A * XA

PB= P’B * XB

P= PA + PB

SKKU Physical Pharmacy Laboratory 성균관대학교 물리약학연구실

Real Solution

> <

•Adhesion•Cohesion

SKKU Physical Pharmacy Laboratory 성균관대학교 물리약학연구실

Negative Deviation

Ex) chloroform + acetone

•dilution effect•attraction•Van der Waals force

>

SKKU Physical Pharmacy Laboratory 성균관대학교 물리약학연구실

Positive Deviation

Ex) benzene + ethanol

•escaping tendency 의 증가

부분 증기압 증가

<

Psolvent = P’solvent * Xsolvent

SKKU Physical Pharmacy Laboratory 성균관대학교 물리약학연구실

Henry’s Law

Psolute = Ksolute * Xsolute

SKKU Physical Pharmacy Laboratory 성균관대학교 물리약학연구실

Distillation of Binary Mixture

Tem

pera

ture

Mole frac-tion

A e f a c B

d v2

bv1

Vapor

Liquid

SKKU Physical Pharmacy Laboratory 성균관대학교 물리약학연구실

Azoetrope

•A mixture of constant composition and constant boiling point ex) HCl in water 20.22% (w/w) bp : 108.58℃

SKKU Physical Pharmacy Laboratory 성균관대학교 물리약학연구실

Psolvent = P’solvent * Xsolvent

= P’solvent * (1-Xsolute) P / P’solvent = Xsolute

측정 : manometer, osmometer, isopiestic method, thermoelectric method

Vapor Pressure

SKKU Physical Pharmacy Laboratory 성균관대학교 물리약학연구실

Boiling Point

• Tb = K * X2

= Kb * m

• Cottrell boiling point appara-tus

SKKU Physical Pharmacy Laboratory 성균관대학교 물리약학연구실

Freezing Point

• Tf = Kf * m

• Beckmann method• Equilibrium method

SKKU Physical Pharmacy Laboratory 성균관대학교 물리약학연구실

Osmotic Pressure

Osmometer

Osmosis vs VP depression

Osmosis

SKKU Physical Pharmacy Laboratory 성균관대학교 물리약학연구실

Van’t Hoff’s Law

πV = n R T

π : osmotic pressure in atm V : volume of solution in liter n : number of moles of solute R : 0.082 (liter*atm) / (mole*deg) T : absolute temperature

π= R T * mMorse Equation

m: Molal conc.

SKKU Physical Pharmacy Laboratory 성균관대학교 물리약학연구실

Molecular weight determination

1) Vapor pressure lowering 이용

P / P’ = X2 = n2 / (n1 + n2) W2 / M2

W1 / M1

W2*M1*P’ W1* P

=

M2 =

SKKU Physical Pharmacy Laboratory 성균관대학교 물리약학연구실

Molecular weight determination

2) Boiling point elevation Freezing point lowering Tb = Kb * m Tf = Kf * m 1000 * W2

W1 * M2

Kb* 1000 * W2 Kf* 1000 * W2

W1* P W1* P

m =

M2 =

이용

=

SKKU Physical Pharmacy Laboratory 성균관대학교 물리약학연구실

3) Osmotic pressure 이용

π = n * R * T / V

n = W2 / M2

W2 * R * T

π * VM2 =

Molecular weight determination