13.4 Activation Energy And Temperature Dependence Of Rate Constants

Question 1

Define activation energy. What role does activation energy play in chemical kinetics?

Answer 1

Activation energy (E(sub a)) is the minimum amount of energy required to initiate a chemical reaction.

Activation energy determines how much energy is required for two molecules to create a rxn. E(sub a) also shows how stable the reactants are. I.e. the lower the E(sub a) the more stable the reactants are

E(sub a) also shows if a reaction is endo/exothermic. If the forward rxn requires less energy than the reverse rxn, then the products are more stable. Which means the reaction will release heat, which make is exothermic

Question 2

Write the Arrhenius equation and define all terms

Answer 2

k=Ae^[-Esub a/(RT)]

E(sub a): activation energy in (KJ/mol)

R: gas constant (8.314 J/(K•mol))

T: absolute temperature

e: base of ln

A: the collision frequency (aka frequency factor)