Physical Chemistry I (TKK-2246) 14/15 Semester 2 Instructor: Rama Oktavian Office Hr.: M – F.13-15

Outlines 1. Review (phase equilibrium) 2. Phase equilibrium (2-comp) 3. p-x diagram 4. T-x diagram

Review Phase diagram

Review Phase diagram

Review Clausius-Clayperon eq.

Review Clausius-Clayperon eq.

Ideal solution Solution Solution - homogeneous mixture of chemical species One phase

Ideal solution Expression of solution composition There are mainly four expressions of the concentration of solute B as following: 1. Mole fractionMole fraction 2. Mass mole concentrationMass mole concentration 3. Amount-of-substance concentrationAmount-of-substance concentration 4. Mass fractionMass fraction

Ideal solution Mole fraction mole fraction The compare of mole of solute B and the total mole of the solution is called mole fraction of solute B, it is also called mole fraction, it has no unit.

Ideal solution Mass mole concentration molality The compare of the mole of solute B and the quantity of solvent A is called mass mole concentration of solute B, its unit is mol.kg-1

Ideal solution Amount-of-substance concentration molarity The compare of the mole of the solute B and the solution volume V is called the mole concentration of solute B, or it is called concentration of solute B, its unit is mol.m -3, but its unit in common use is mol.dm -3

Ideal solution Mass fraction mass fraction The compare of the mass of solute B and the total mass of solution is called the mass fraction of solute B

Ideal solution

Solution Vapor pressure of pure substance Only solvent is volatile

Ideal solution Solution Raoult’s law

Ideal solution Raoult’s law under the fixed temperature, in the dilute solution, the vapor pressure of the solvent p*A is equal to the value vapor pressure of pure solvent multiplies the mole fraction X A of the solvent.

Ideal solution Solution Non-ideal solutionIdeal solution

Solution Consider a solution composed of several volatile substances the total pressure the ideal solution is defined by the requirement that each component obey Raoult's law Solution Ideality => Uniformity in Intermolecular forces. (Binary: A-A, B-B, A-B all the same) Typically, molecules are similar in size and shape Examples: benzene & toluene, hexane and heptane

Ideal solution Solution

Ideal solution Solution General characters of mixing solution:

Binary solution Binary Solution Solution contains two components For ideal binary solution the total pressure over the solution is p

Binary solution Binary Solution

Binary solution Binary Solution

Binary solution Binary Solution

Binary solution Binary Solution Gaseous phase Partial pressure of component 1

Binary solution Binary Solution Gibbs phase rule for two components F = C – P + 2 C = 2 F = 4 - P

Binary solution Binary Solution F = 4 - P P = 2F = 2

Binary solution Deviations from Raoult’s Law CS 2 and dimethoxymethane: Positive deviation from ideal (Raoult’s Law) behavior. trichloromethane/acetone: Negative deviation from ideal (Raoult’s Law) behavior.

Ideal solution

Binary solution Changes in state as the pressure is reduced isothermally P-x,y diagram

Binary solution Lever rule To determine the number of vapor and liquid at equilibrium condition

Binary solution Lever rule

Binary solution Lever rule

Binary solution Example problem

Binary solution Example problem

Binary solution T-x diagram

Binary solution Azeotropes

Solution Colligative properties is the chemical potential of the solvent in the solution For an ideal-dilute solution

Solution Freezing point depression

Solution Freezing point depression If solution is very dilute