Ch 12 Solutions 12.1 Types of Mixtures Solutions are homogeneous mixtures 2 or + substances uniform throughout Soluble: Capable of being dissolved Solute: Being dissolved Solvent: Doing the dissolving Types of solutions Can be solids (metal alloys), liquids (salt water), or gases (air)

Colloids Intermediate size between solution and suspension 1nm-100nm in diameter Dispersion phase (particles) & dispersion medium (liquid) Appears cloudy Ex: emulsion (liquid in liquid), milk, fog, liquid aerosols

Tyndall Effect Light is scattered by particles of colloid Figure 1.6 Tyndall Effect Light is scattered by particles of colloid Ex headlight scatter particles in fog Brownian motion: motion due to collisions of rapidly moving particles in colloids

Separating Solutions, Colloids, and Suspensions Shine light colloid vs solution Settles out suspension

Electrolytes Nonelectrolytes Dissolves in water to make a solution Conducts an electric current readily Nonelectrolytes Does not conduct an electric current

12.2 The Solution Process Factors affecting dissolving Increase the surface area: more surface area of solute in contact with solvent it dissolves faster Agitating the solution: mixing/stirring puts more of surface of solute in contact with solvent Heating the solvent: as temp increases the solvent molecules speed up/greater KE and more collisions

Supersaturated Solution Solution Equilibrium Physical state dissolution = crystallization rate Saturated Solution Max amount of dissolved solute Unsaturated Solution Less then max amount of dissolved solute Supersaturated Solution More dissolved solute then usual for given conditions

Solubility: “likes dissolve likes” Ionic compounds Water is the solvent: hydration Ionic substances form crystals with water: hydrate CuSO4 . 5H2O

Nonpolar solutions Liquids Ionic compounds not soluble in nonpolar solvent Nonpolar solvent molecules not attract/cannot break bonds of ions holding crystal together Liquids Immiscible: liquids not soluble in each other Miscible: liquids that dissolve freely in one another

Affects of Pressure Henry’s Law Pressure has little effect Gas + solvent ↔ solution Henry’s Law Solubility of gas in liquid is directly proportional to partial pressure of the gas on the surface of liquid Have constant temp Effervescence: escape of gas from liquid, ex soda

Effects of Temperature Increase temp decreases gas solubility Increase temp increase liquid/solid solubility usually Energy influence Solvated: solute surrounded by solvent Enthalpy of solution: E absorbed by heat of soln when solute dissolves in solvent

12.3 Concentration of Solutions Concentration: amount of solute in solvent Molarity (M) Number of moles in 1 L of solution

Molality (m) number of moles in 1 kg of solution