skku physical pharmacy laboratory 성균관대학교 물리약학연구실

SKKU Physical Pharmacy Laboratory 성균관대학교 물리약학연구실

Chapter 5.Solutions of Nonelectrolytes


Contents

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


Solution

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

milk


Properties of Solutions

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


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.


Equivalent Weights

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

combining with 1.008 g of hydrogen

• Equivalent weight = atomic weight / valence


Ideal Solution

NaCl0.01mole

1 L

“ 분자간의 인력이 균일”


Escaping Tendency

Temperature, Concentration, Pressure…..


Vapor Pressure

Equilibriumvapor pressure


Raoult’s Law

PA= P’A * XA

PB= P’B * XB

P= PA + PB


Real Solution

> <

•Adhesion•Cohesion


Negative Deviation

Ex) chloroform + acetone

•dilution effect•attraction•Van der Waals force

>


Positive Deviation

Ex) benzene + ethanol

•escaping tendency 의 증가

부분 증기압 증가

<

Psolvent = P’solvent * Xsolvent


Henry’s Law

Psolute = Ksolute * Xsolute


Distillation of Binary Mixture

Tem

pera

ture

Mole frac-tion

A e f a c B

d v2

bv1

Vapor

Liquid


Azoetrope

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


Psolvent = P’solvent * Xsolvent

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

측정 : manometer, osmometer, isopiestic method, thermoelectric method

Vapor Pressure


Boiling Point

• Tb = K * X2

= Kb * m

• Cottrell boiling point appara-tus


Freezing Point

• Tf = Kf * m

• Beckmann method• Equilibrium method


Osmotic Pressure

Osmometer

Osmosis vs VP depression

Osmosis


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.


Molecular weight determination

1) Vapor pressure lowering 이용

P / P’ = X2 = n2 / (n1 + n2) W2 / M2

W1 / M1

W2*M1*P’ W1* P

=

M2 =



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

=


3) Osmotic pressure 이용

π = n * R * T / V

n = W2 / M2

W2 * R * T

π * VM2 =


skku physical pharmacy laboratory 성균관대학교 물리약학연구실

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