chemistry - unit 1 - section 5: kinetics

Definition of Rate of reaction

The change of concentration/amount of a reactant or product per unit time

The rate of reaction formula

Amount of reaction or product made/ time

Collision theory

1. For a reaction to occur the particle must collide in the right direction

2. They must also have a minimum amount of kinetic energy

Definition of activation energy

The minimum amount of energy required for a reaction to occur

Definition of Energy profile diagram

Show the energy change in a reaction

• reactions that have a low activation energy need less energy to break the bonds

Maxwell-Boltzmann Distribution

• shows the energy in gas particles

• Particles of gas in a sample move at different speeds and have different amount of kinetic energy

• If plotted on the graph, it doesn’t start at 0,0 as no particles have zero kinetic energy

• The area under the curve is equal to the total number of molecules

What affects the rate of the Maxwell-Boltzmann distribution

Temperature:

• The higher temp. A larger proportion of the molecules will have energy greater than the activation energy. larger area under the curve beyond the activation energy. The graph shifts to the right

• The lower temp. A smaller proportion of the molecules will have energy greater than the activation energy. Smaller area under the curve beyond the activation energy. Graph shifts to the left

Why do we get a faster rate of reaction when temperature is increased?

Particles move around more at higher temperatures. They collide more often. The combination