Maxwell-Boltzmann; Temperature and Catalysts

Activation Energy Collisions only result in a reaction if the particles collide with enough energy to get the reaction started. This minimum energy required is called the activation energy for the reaction. Only a fraction of the total population of a chemical species will be able to collide with enough energy to react (E ≥ Ea)

Maxwell-Boltzmann Distribution In any system, the particles present will have a very wide range of energies. For gases, this can be shown on a graph called the Maxwell-Boltzmann Distribution which is a plot of the number of particles having each particular energy.

The Maxwell-Boltzmann Distribution and Activation Energy Notice that the large majority of the particles don't have enough energy to react when they collide. To enable them to react we either have to change the shape of the curve, or move the activation energy further to the left.

M-B Distribution and Temperature Increasing the temperature: increases the average kinetic energy of the gas (slight shift to the right) Increases the number of particles whose energy exceeds the activation energy

Catalysts and Activation Energy To increase the rate of a reaction you need to increase the proportion of successful collisions. Catalysts increase the rate of reaction by providing an alternative way for the reaction to happen which has a lower activation energy.

M-B Distribution and Catalysts

Summary Maxwell-Boltzmann Energy Distribution Curve Temperature distribution of a population of a chemical by energy Used to show effect of temperature and catalysts on the rate of a chemical reaction Temperature changes average kinetic energy of population shifts and distorts the M-B Distribution curve changes the proportion of particles with Ea. Catalysts provide alternative pathway with a lower the activation energy Ea on M-B curve is shifted left no effect on distribution curve itself