Solutions Details

Making a solution Solvent, solute, and something to contain both. Factors that affect solvation Agitation Temperature of solvent/solution Surface area of solute

Degrees of saturation Saturated: holds maximum amount of solute in given solvent at constant temperature and pressure Solubility: the amt. of solute that dissolves in a given solvent at a specified temperature and pressure to give a saturated solution Frequently given as grams/liter

More on saturation If a solution contains less than the saturation amount of solute, it is called unsaturated If you have a saturated solution, and cool if slowly, you can produce a supersaturated solution, which hold more solute than it “should” be able to. Crystallization will occur if a suitable seed is provided.

Liquid Solutions Two liquids are miscible if they dissolve in each other in all proportions The liquid in higher amount is considered the solvent Liquids that are insoluble in each other are immiscible

Solubility Factors Temperature: as temperature increases: most solids are more soluble Most gases are less soluble Pressure: only affects gases: Henry’s law: S1/P1 = S2/P2 As the pressure above the liquid increases, the solubility of the gas increases.

Concentration: molarity Molarity (M) = mol solute/lit solution Dilutions: (molarity)(volume) = mol

Other calculations of concentration Molality m= moles solute/kg solvent

Concentration: Percent solutions % volume: vol.solute/vol. soln.·100% % mass: Mass solute/mass soln.·100%

Colligative Properties of Solutions Vapor-pressure reduction This occurs because the solute causes there to be different intermolecular attractions than would exist in pure solvent…ionic compounds, which dissociate, have a greater effect than non-dissociating solutes, such as sugar. The decrease in vapor pressure is proportional to the amt. of solute present in the solution

Colligative Properties of Solutions Freezing-point depression The amount of lowering of a freezing point due to the same disruption and/or attractions of a solute in a solvent Again, proportional to amount Think about the salting of roads and sidewalks!

Colligative Properties of Solutions Boiling point elevation Since the addition of a nonvolatile solute lowers the vapor pressure, this means that it takes more energy for the solution to reach the boiling point Again, the magnitude of the elevation is proportional to the amt. of solute dissolved in the solution