Kinetics

What speeds up a Chemical Reaction?

1. addition of a catalyst

   • Catalyst provide a different pathway of lower activation energy (i.e. enzymes)

2. Increase the concentration of the reactants

3. Increase the temperature of the reactants

4. Increase the surface area

   • Grind it up into a powder

Reaction Orders

• Zero order → concentration has no effect on rate

• First Order → Doubling concentration doubles the rate

• Second Order → Doubling concentration quadruples the rate

• Third Order→ Doubling concentration changes the rate x8

• 1st Order reactions = half-life equation!
  t1/2 = 0.693/k

Mechanisms

• Transition states or intermediate

  • Formed and consumed durring a reaction; temporary chemical

• ELementary Steps

  • Each step in a Mechanism

Rate laws = slow step

Order of Elementary Steps in a Mechanism

• Unimolecular - 1st order

  • 1 reactant with a coefficient of 1

• Bimolecular - 2nd order

  • reactant coefficients add up to 2

• Termolecular - 3rd order

  • reactant coefficients add up to 3

Collision Theory

Reactants must collide

• With sufficient energy

• Frequency

• In the right orientation

Activation Energy - minimum energy needed to start a reaction

Reactions involving 2 or more molecules are likely to happen in multiple steps

Rate Law

A + B + C → D

Exponent = order

K is a constant rate