Chapter 5. Solutions of Nonelectrolytes

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

Solution Composition Classification Solvent Solute 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 Symbol Molarity Normality Molality Mole fration Mole percent Percent M, c N m X, N % w/w, v/v, w/v Characteristics 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 NaCl 0.01mole “분자간의 인력이 균일” 1 L

Escaping Tendency Temperature, Concentration, Pressure…..

Vapor Pressure Equilibrium vapor 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 < Psolvent = P’solvent * Xsolvent Ex) benzene + ethanol escaping tendency의 증가 부분 증기압 증가 Psolvent = P’solvent * Xsolvent

Henry’s Law Psolute = Ksolute * Xsolute

Distillation of Binary Mixture v2 Vapor d v1 Liquid b Temperature A e f a c B Mole fraction

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

Vapor Pressure Psolvent = P’solvent * Xsolvent P / P’solvent = Xsolute 측정: manometer, osmometer, isopiestic method, thermoelectric method

Boiling Point Tb = K * X2 = Kb * m Cottrell boiling point apparatus

Freezing Point Tf = Kf * m Beckmann method Equilibrium method

Osmotic Pressure Osmosis Osmosis vs VP depression Osmometer

π= R T * m 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 * m Morse 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 =

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 =

Molecular weight determination 3) Osmotic pressure 이용 π = n * R * T / V n = W2 / M2 W2 * R * T π * V M2 =