Factors Affecting Solubility

What is Solubility?• Describes the amount of solute that dissolves

in a solvent.

Driving Forces of SolubilityEnthalpy:

• Total energy of a chemical system• The enthalpy change (∆H) is the

amount of heat released or absorbed when a chemical reaction occurs

at constant pressure.

Driving Forces of SolubilityEntropy:

• Randomness• Things like to become more random.

Entropy

*Entropy increases as a substance changes from solid to liquid to gas

When a solid dissolves, attractive forces are weakened, and randomness increases.

As ice melts, entropy increases

*If exothermic (gives off heat), dissolving takes place.

*Endothermic (absorbs heat) can occur if randomness term is greater.

Youtube Video - Dissolving in Endothermic Reaction

Temperature and SolubilityAbout 95% of solids are most soluble at high

temperatures.

Solids = direct relationship for temperature and solubility

Temperature and SolubilityGases have no crystal lattice energy.

Dissolving of a gas is generally exothermic, and favored at lower temperatures.

Gases = indirect relationship for temperature and solubility

Pressure and SolubilityPressure only affects the solubility of gases.

As air pressure increases, solubility of a gas increases.

Pressure and Carbonation Video

DirectRelationship

Nature and SolubilityWhether polar or nonpolar.

*Like dissolves like

The rule of thumb is that "like dissolves like". Polar/ionic solvents dissolve polar/ionic solutes and non-polar solvents dissolve non-polar solutes.

Water Dissolving Salt Video

Oil Dissolution Video

Oil In Water Video