Unit 5 - Reaction Energy

exothermic reaction

A reaction that releases energy in the form of heat, light, or sound.

endothermic reaction

A reaction that absorbs energy in the form of heat.

enthalpy

The total heat content in a system; energy changes that occur during a reaction.

Hess’s Law

States that the enthalpy change for an overall process is the sum of the ΔH values for each step of the process.

collision theory

A theory that states particles must collide for a chemical reaction to occur.

activation energy

The minimum amount of energy needed to initiate a chemical reaction.

catalyst

A substance that changes the rate of a chemical reaction without being consumed.

reaction rate

The speed at which a chemical reaction occurs.

thermochemical equation

An equation that includes the value of change in enthalpy (ΔH) and the physical states of reactants and products.

calorimeter

A device used to measure the change in enthalpy during a reaction under constant pressure.

bond energies

The energy required to break bonds in a substance, which can indicate the stability of products in a reaction.

reaction efficiency

A measure of how effectively a chemical reaction proceeds to completion and produces the intended products.

rate law

An expression that describes the relationship between the rate of a reaction and the concentration of its reactants.

chemical kinetics

The study of the speed of chemical reactions and the factors affecting this speed.