Solutions

Vocabulary Solute Solvent Solubility Saturated Supersaturated Unsaturated Colligative property

Vocabulary Aqueous Concentrated Dilute Dilution Molarity m/m percent m/v percent

Vocabulary v/v percent Molality Normality Miscible Immiscible

Solubility How much will dissolve in a specific amount of a specific solvent at a given temperature. Typically reported as g/100 g solvent Solubility of solids and liquids increase with temperature. Solubility of a gas decreases with temperature

Rate of solution Solids and liquids dissolve faster when: Temperature is increased It is shaken or stirred Solute is ground up

Solubility curve

How stuff dissolves

9 types of solution Solute Solvent Example Gas Gas air Liquid Gas humidity Solid Gas ----- Gas Liquid soda Liquid Liquid vinegar, antifreeze Solid Liquid Kool Aid Gas Solid ----- Liquid Solid Amalgam Solid Solid Alloy: Brass, steel

Solution states Phase of matter of final solution

Molarity M Moles solute per liter of solution Mol/L

Molality m Moles solute per kg solvent Used with colligative properties

Colligative Properties Freezing point depression Boiling point elevation Vapor pressure depression Read p 552-553 Depends ONLY on the number of particles in solution, not what they are. Dissolving 1 mole of NaCl in water results in 2 moles of dissolved particles: Na and Cl

Freezing point depression Calculate molality Multiply by van’t Hoff factor Multiply by freezing point depression constant (0.512 oC/m for water) Subtract from 0oC

Boiling point elevation Calculate molality Multiply by van’t Hoff factor Multiply by boiling point elevation constant (1.86 oC/m for water) Add to 100oC

Dilutions The way that always works: determine moles, then adjust volume with water. Shortcut : Conc x volume = Conc x volume Make sure you are working in the same units Stock solution: the concentrated solution of known concentration. It is the starting point for dilutions.

Solution stoichiometry Use molarity to find moles of known Use stoichiometry to find moles of unknown May have to use moles of unknown and volume to determine molarity of unknown if asked (rare)