A suspension is a mixture containing particles that settle out if left undisturbed. A suspension mixture can also be filtered. 1

A solution is a homogeneous mixture (same phases: solid, liquid, gas) A COLLOID MIXTURE IS NOT A SOLUTION MMMMMMM… A solution is a homogeneous mixture (same phases: solid, liquid, gas) A colloid mixture would be heterogeneous (different phases) Think salt water versus septic tank water. 2

A heterogeneous mixture of mid-sized solution particles COLLOID WHAT WOULD HAPPEN IF WE ADDED SALT TO THIS? 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. 3

The erratic movement of colloid particles BROWNIAN MOTION The erratic movement of colloid particles 4

Light is scattered through a colloid mixture. 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. 5

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IMMISCIBLE MISCIBLE 7

Two liquids that are soluble in each other in any proportion. IMMISCIBLE MISCIBLE Two liquids that can be mixed together but separate shortly after they are mixed. Two liquids that are soluble in each other in any proportion. 8

How much solute is dissolved in a specific amount of solution. CONCENTRATION How much solute is dissolved in a specific amount of solution. % by mass % by volume Molarity Dilution Equation 9

DILUTING STOCK SOLUTIONS M1V1 = M2V2 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. 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? 10

surrounding solute particles with solvent particles. “LIKE DISSOLVES LIKE” The process of surrounding solute particles with solvent particles. 11

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ENDO- AND EXOTHERMIC: THE HEAT OF SOLUTION 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. 13

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. 14

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.

Colligative Properties On adding a solute to a solvent, the properties of the solvent are modified. Vapor pressure decreases Melting point decreases Boiling point increases Osmosis is possible (osmotic pressure) These changes are called COLLIGATIVE PROPERTIES. They depend only on the NUMBER of solute particles relative to solvent particles, not on the KIND of solute particles.

Change in Freezing Point Ethylene glycol/water solution Pure water The freezing point of a solution is LOWER than that of the pure solvent

Change in Freezing Point Common Applications of Freezing Point Depression Ethylene glycol – deadly to small animals Propylene glycol

Change in Freezing Point Common Applications of Freezing Point Depression 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? sand, SiO2 Rock salt, NaCl Ice Melt, CaCl2

Change in Boiling Point Common Applications of Boiling Point Elevation

Boiling Point Elevation and Freezing Point Depression ∆T = K•m•i i = van’t Hoff factor = number of particles produced per molecule/formula unit. For covalent compounds, i = 1. For ionic compounds, i = the number of ions present (both + and -) Compound Theoretical Value of i glycol 1 NaCl 2 CaCl2 3 Ca3(PO4)2 5

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?

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