Chemistry - Thermochemistry Terms Review

Enthalpy (△H)

Heat released during a reaction

Heat

The transfer of energy between two substances based on the change in temperature

Endothermic

Products have MORE potential energy than reactants (heat listed on the left side of equation)

Exothermic

Products have LESS potential energy than reactants (heat listed on right side of the equation, -△H)

Entropy

How ordered/disordered a system is

Four factors of Entropy

• Amount of Molecules

• Variety of Molecules

• Temperature

• State of Matter changes (gas > liquid > solid)

Gibbs free energy

Amount of energy available to do work

Gibb’s Formula

△G = △H-T△S

-△H, +△S, -△G

Always spontaneous

+△H, -△S, +△G

Never spontaneous

-△H, -△S, -△G

Spontaneous at low temperatures

+△H, +△S, -△G

Spontaneous at high temperatures