Solutions

A solution is a homogeneous mixture in which one substance is dissolved in another. The dissolved substance is completely dispersed, i.e., its composition is the same throughout its volume. Usually a solid is dissolved in a liquid, but liquids can be dissolved in other liquids and gases can be dissolved in a liquid as well.

Definitions Solvent: Liquid in which a substance is dissolved Solute: Dissolved solid Examples of solutions: Sea water Drinking water Soft drinks (2 types) Air

Types of Solutions Concentrated solution: Composed of a high percentage of solute Dilute Solution Composed of a low percentage of solute Solubility and Saturation The maximum amount of solute which will dissolve in a fixed quantity of the given solvent at a specified temperature Expressed in g of solute/kg of water or g/100g of water

Saturated Solution No more solute can dissolve Unsaturated Solution Still more solute can dissolve Supersaturated Solution Contains more solute than can dissolve at a particular temperature

A solubility curve shows the relationship of all three solutions: Temperature (°C) Solubility (g/kg of H 2 O) x supersaturated x unsaturated Saturated (on the line)

Factors Affecting Solubility Pressure Only solutions in which a gas is dissolved in liquids (or solids) are affected by pressure By increasing the pressure, the solubility of the gas increases. ex. Carbonated drinks -if pressure is released (decreased), gas from the liquid escapes

Temperature Effect depends on the type of solution Solubility of a solid (in a liquid) is usually higher at warmer temperatures than at cooler temp. Gases work in the opposite manner – that is, if Temp  then solubility  Again, a solubility curve will determine the solubility of a substance at a particular temperature

Solvent-Solute Interaction “Like dissolves like” Substances with similar intermolecular attractive forces tend to be soluble in one another ex. Non-polar solvents dissolve non- polar solutes Polar solvents dissolve polar and ionic solutes