Solutions

What are solutions?

• Solution – a homogeneous mixture of two or more substances in a single phase.

• Solutions contain two components: a solute and a solvent.

• Solute – the substance dissolved in a solution.

• Solvent – the dissolving medium in a solution.

Types of Solutions

• Solutions may be any combination of gases, liquids, or solids

• Water is the universal (most common) solvent.

Solute Solvent

Examples

Gas Gas Air (O2,N2)

Gas Liquid Sodas

Liquid Gas H2O in air

Liquid Liquid Alcohol in water

Liquid Solid Dental fillings

Solid Liquid Saltwater

Solid Solid Brass

Other Mixtures

• Suspension – a heterogeneous mixture where the particles in the solvent are so large that they settle out unless the mixture is constantly stirred.

• Colloid – a mixture in which particles of intermediate size do not settle in a mixture.

Electrolytes

• Electrolyte – a substance that dissolves in water to give a solution that conducts electric current.

• Nonelectrolyte – a substance that dissolves in water to give a solution that does not conduct an electric current.

Factors That Affect Solubility

• Surface area – because the dissolving process happens at the surface area of a solute, crushing or grinding the solute speeds up the rate of dissolution.

• Agitation – stirring or shaking helps spread out the solute particles which increases the rate of dissolution.

• Heating – speeds up the particle motion therefore helping it dissolve the solute.

• Pressure – changes how gases dissolve in liquids.

Saturation

• Saturated solution – a solution that contains the maximum amount of dissolved solute.

• Supersaturated solution – a solution that contains more dissolved solute than a saturated solution, eventually excess solute will precipitate out.

• Unsaturated solution – a solution that does not have the maximum amount of dissolved solute.