Drill – 4/5/11 1. What is dilution? 2. How does the amount of solute change? 3. How does the amount of solvent change?

Solutions Chapter 12

Why do some things dissolve? “Like dissolves like.”  Nonpolar solvents dissolve Nonpolar solutes (non polar molecules).  Polar solvents dissolve Polar solutes (polar molecules / ionic compounds)

Remember… Nonpolar – has a neutral net charge. ex: all nonpolar covalent molecules Polar – particles have a positively and negatively charged side. ex: any ionic compound, polar covalent molecules

Solubility Values  The amount of substance required to form a saturated solution with a specific amount of solvent at a specified temperature  Grams of solute per grams of solvent

Effects of Pressure on Solubility  No effect on solids and liquids  Increase in pressure for gases = increase in solubility in liquids  Henry’s Law – The solubility of a gas is directly proportional to the pressure of that gas on the surface of liquid  Ex. Bottling soda

Solubility of Solids in Liquids  Effect of Temperature on Solid Solubility: increases solubility (usually) as temp. increases.

Solubility of Gases in Liquids  Effect of Temperature on Gas Solubility: Decreases solubility (usually) as temp. increases.

 Solubility Curve WS

Concentration A measure of the amount of solute in a given amount of solvent or solution. (General terms dilute and concentrated are general and difficult to transfer between different types of solutions.)

Molarity  The number of moles of solute in one liter of solution.  Molarity: Molar (M)  Molarity = amount of solute (mol) volume of solution (L) volume of solution (L)

Molality  The number of moles of solute per kilogram of solvent.  molality: molal ( m )  molality = amount of solute (mol) mass of solvent (kg) mass of solvent (kg)

Dilution with Molarity  M = mol/V can be rearranged to mol = M×V If we don’t change the amount of solute (which is the case with dilution) then moles before = moles after mol 1 = mol 2 M 1 V 1 = M 2 V 2