Chemistry Unit 14: Thermochemistry

Thermochemical equation

Chemical equation including energy change in reaction.

Enthalpy (H)

Heat content of a substance at constant pressure.

ΔH

Change in enthalpy during a reaction.

Exothermic Reactions

Reactions that release energy, ΔH is negative.

Endothermic Reactions

Reactions that absorb energy, ΔH is positive.

Chemical Potential Energy

Stored energy in chemical bonds of substances.

Law of Conservation of Energy

Energy cannot be created or destroyed, only transformed.

Calorimetry

Measurement of heat changes in chemical processes.

Specific heat (c)

Heat required to raise 1g of substance by 1°C.

Heating curve

Graph showing temperature changes during phase transitions.

Molar heat of fusion (ΔHfus)

Energy required to melt a substance from solid to liquid.

Molar heat of vaporization (ΔHvap)

Energy required to vaporize a substance from liquid to gas.

Coffee Cup Calorimeter

Constant-pressure calorimeter using water to measure heat.

Bomb Calorimeter

Constant-volume calorimeter measuring heat from combustion.

Thermal equilibrium

State when two objects reach the same temperature.

Hess's Law

The overall enthalpy change in a reaction is equal to the sum of enthalpy changes for the individual steps in the process