18/19 Reaction Rates and Catalysts

Rate of reaction definition

The change in concentration of reactants or products over time.

5 ways to increase rate of reaction?

Increase surface area, increase concentration, increase pressure, increase temperature, add a catalyst.

5 ways in which reaction rate can be measured

Mass loss, volume of gas produced, colour change, concentration change, pH change.

What does collision theory state?

For a reaction to occur, reacting particles must collide with sufficient energy to overcome the activation energy and with an appropriate orientation.

Activation energy definition

The minimum amount of energy that colliding particles must possess for a successful collision and reaction to occur.

Catalyst definition

A substance that increases the rate of reaction by offering an alternate reaction pathway with a lower activation energy.

What does increasing concentration, surface area or pressure result in?

An increase in the frequency of collisions and the number of successful collisions.

What does increasing temperature result in?

An increase in the frequency of collisions, the energy of collisions, and the number of successful collisions.

How do catalysts speed up reactions?

They provide an alternate reaction pathway with a lower activation energy, so a greater proportion of collisions exceed the activation energy, so the number of successful collisions increases.