A suspension is a mixture containing particles that settle out if left undisturbed. A suspension mixture can also be filtered.

A COLLOID MIXTURE IS NOT A SOLUTION

A solution is a homogeneous mixture (same phases: solid, liquid, gas)

A colloid mixture would be heterogeneous (different phases)

MMMMMMM…

Think salt water versus septic tank water.

COLLOID

A heterogeneous mixture of mid-sized solution particles

Adding an electrolyte will disrupt the electrostatic charges that hold the solute in the solution.

Heating it up will also cause a colloid to settle.

WHAT WOULD HAPPEN IF WE ADDED SALT TO THIS?

BROWNIAN MOTION

The erratic movement of colloid particles

TYNDALL EFFECT

Light is scattered through a colloid mixture.

If a colloid mixture were so dilute that it looked like an aqueous solution, a flashlight can solve the mystery.

IMMISCIBLE MISCIBLE

IMMISCIBLE

Two liquids that can be mixed together but separate shortly after they are mixed.

MISCIBLE

Two liquids that are soluble in each other in any proportion.

CONCENTRATION

How much solute is dissolved in a specific amount of solution.

% by mass % by volume Molarity Dilution Equation

DILUTING STOCK SOLUTIONS

If you know the concentration and volume of the solution you want to prepare, you can calculate the volume of stock solution you will need.

M1V1 = M2V21V1 = M2V2

What volume, in milliliters, of 2.00 M calcium chloride (CaCl2 ) stock solution would you use to make 0.50 L of 0.300M calcium chloride solution?

“LIKE DISSOLVES LIKE”

The process of surrounding

solute particles with solvent particles.

ENDO- AND EXOTHERMIC:

Energy is needed to make the solvent particles ‘open up’ to allow a solute particle to get squeezed in between the solvent particles. This is an endothermic process (takes energy).

When the solvent particles mix, the particles attract each other, giving off energy (exothermic process)

The overall energy change that occurs during the formation of the solution is called the Heat of Solution.

To increase the rate of solvation shake it up, increase the surface area, or heat it up.

THE HEAT OF SOLUTION

Solvation

Solubility of gases

Gases are less soluble at higher temperatures. The velocity (speed or kinetic energy) of the gas particles is so great that the gas escapes the solution.

Solvation

Pressure and Henry’s law Pressure affects the

solubility of gaseous solutes in solutions.

The solubility of a gas in any solvent increases as its external pressure (the pressure above the solution) increases.

Solvation

Henry’s Law: at a given temperature, the solubility (S) of a gas in a liquid is directly proportional to the pressure (P) of the gas above the liquid.

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Colligative PropertiesColligative PropertiesOn adding a solute to a solvent, the properties On adding a solute to a solvent, the properties

of the solvent are modified.of the solvent are modified.

• Vapor pressure Vapor pressure decreasesdecreases

• Melting point Melting point decreasesdecreases

• Boiling point Boiling point increasesincreases

• Osmosis is possible (osmotic pressure)Osmosis is possible (osmotic pressure)

These changes are called These changes are called COLLIGATIVE COLLIGATIVE PROPERTIESPROPERTIES. .

They depend only on the They depend only on the NUMBERNUMBER of solute of solute particles relative to solvent particles, not on particles relative to solvent particles, not on the the KINDKIND of solute particles. of solute particles.

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Change in Freezing Change in Freezing Point Point

The freezing point of a solution is The freezing point of a solution is LOWERLOWER than that of the pure solventthan that of the pure solvent

Pure waterPure waterEthylene glycol/water Ethylene glycol/water

solutionsolution

19Change in Freezing Change in Freezing Point Point

Common Applications Common Applications of Freezing Point of Freezing Point DepressionDepression

Propylene glycol

Ethylene glycol – deadly to small animals

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Common Applications Common Applications of Freezing Point of Freezing Point DepressionDepression

Which would you use for the streets of Bloomington to lower the freezing point of ice and why? Would the temperature make any difference in your decision?

a) sand, SiO2

b) Rock salt, NaCl

c) Ice Melt, CaCl2

Change in Freezing Change in Freezing Point Point

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Change in Boiling Point Change in Boiling Point Common Applications Common Applications

of Boiling Point of Boiling Point ElevationElevation

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Boiling Point Elevation Boiling Point Elevation and Freezing Point and Freezing Point

DepressionDepression ∆∆T = K•m•iT = K•m•ii = van’t Hoff factor = number of particles i = van’t Hoff factor = number of particles

produced per molecule/formula unit. For produced per molecule/formula unit. For covalent compounds, i = 1. For ionic covalent compounds, i = 1. For ionic compounds, i = the number of ions compounds, i = the number of ions present (both + and -)present (both + and -)

CompoundCompound Theoretical Value of iTheoretical Value of iglycolglycol 11NaClNaCl 22

CaClCaCl22 33

CaCa33(PO(PO44))22 55

Colligative Properties

Sodium chloride (NaCl) is often used to prevent icy roads and to freeze ice cream.

What are the general effects of adding sugar to water?

Sodium chloride? Calcium chloride? Lithium

phosphate?