AP Notes Chapter 14 Solutions and Their Behavior

Solution a homogeneous mixture of two or more components Solute component(s) present in lesser quantity Solvent component present in greater quantity

A saturated solution contains the maximum quantity of solute that dissolves at that temperature. An unsaturated solution contains less than the maximum quantity of solute that dissolves at that temperature. Supersaturated Solutions contain more than is possible and are unstable.

Liquid Solutions 1. molarity, M

2. mass %

3. mole fraction, ( A )

4. molality, m

Molar Soln Molal Soln

Ideal Solution P(A) 0 is the VP of volatile solvent A at a particular temperature

Properties of Ideal Solutions if P(A) is the vapor pressure of a solution of volatile solvent A, and non-volatile solute B, then P(A) (A)

or P(A) = (A). P(A) 0 [Raoults Law] VP Solution

for a solution where 2 components are volatile P(T) = P(A) + P(B) = (A). P(A) 0 + (B). P(B) 0

Ideal Solutions

Positive deviation Real Solutions Negative deviation

Properties of Ideal Solutions if P(A) is the vapor pressure of a solution of volatile solvent A, and non-volatile solute B, then P(A) (A)

Properties of Ideal Solutions 2. NO volume changes occur during the solution process

Properties of Ideal Solutions 3. NO heat is evolved or absorbed during the solution process

Raoults Law is valid only for VERY dilute solutions or some nonpolar - nonpolar solutions

Solubility Factors like dissolves like

Polar H 2 O Non-polar I 2 Non-polar CCl 4 Polar H 2 O Non-polar I2 Non-polar CCl 4 Solvent Extraction

O // H 2 C-O-C-R | O | // H 2 C-O-C-R | O | // H 2 C-O-C-R a fat + 3 NaOH R = (CH 2 ) 16 CH 3

H 2 C-O-H | H 2 C-O-H | H 2 C-O-H O \\ + 3 R-C-O - Na + a soap

Surfactants Surface acting agents Surface acting agents Lowers surface tension Lowers surface tension Enables solvation Enables solvation Those used for cleaning are commonly called detergents Those used for cleaning are commonly called detergents

Temperature

SOLIDSSOLIDS

GASESGASES

Pressure S g = k H P g Henrys Law

Colligative Properties

Property whose magnitude depends solely on the concentration of particles, NOT on the nature of the particles

Electrolyte solute that forms ions in solution which conducts a current

Non-Electrolyte solute that remains as molecules in solution which does NOT conduct a current

molality moles of substance measured through mass before solution process takes place

Colligative Properties of Non-Electrolytes

1. Vapor Pressure Lowering VP Lowering

1. Vapor Pressure Lowering A = solvent ; B = solute A + B = 1

1. Vapor Pressure Lowering A = solvent ; B = solute A + B = 1 A = 1 - B

but: P A = A P o A thus: P A = (1 - B ) P o A or: P A = P o A - B P o A

NOTE: the lowering of the vapor pressure of the pure solvent A is a function only of B (solute)

boiling point temperature where vapor pressure of solvent equals the atmospheric pressure

2. Boiling Point Elevation

T bp m

T bp = k bp m where k bp = a constant that is a function of the solvent

units on k bp ?

Freezing Water Freezing Solution 3. Freezing Point Depression

T fp m

T fp k fp m k fp = freezing point constant

k fp = k bp for the same solvent

OSMOSIS the flow of solvent into a solution through a semi-permeable membrane

Examples Egg Rxn Microscopic Perspective Egg Explanation Macroscopic Perspective

4. Osmotic Pressure the pressure that must be applied to a solution to stop osmosis

Reverse Osmosis

4. Osmotic Pressure = osmotic pressure V = n B R T

or = M B R T M B = Molarity of solute

Colligative Properties of Electrolytes

Must adjust for degree of dissociation

i = vant Hoff factor T bp = i k bp m T fp = i k fp m = i

Compound i NaCl MgSO 4 MgCl 2 FeCl 3

Compound i NaCl 1.9 MgSO MgCl FeCl 3 3.4