Chem 2 - Reaction rates, Salts and Electrolysis - Collision Theory

The rate of reaction depends on how often and how hard the reacting particles collide with each other. Particles have to collide in order to react, and they have to collide hard enough (with enough energy)

Higher Temperature increases collisions:

- When the temperature increases, the particles all move quicker. If they're moving quicker they will start to collide more often

Higher concentration (or pressure) increases collisions:

- If a solution is made more concentrated it means there are more particles of a reactant knocking about between the water molecules which makes collisions between the important particles more likely.

- In a gas, increasing the pressure means the particles are more squashed up together so there will be more frequent collisions

Large surface area increases collisions:

- If one of the reactants is a solid, then breaking it up into smaller pieces will increase the total surface area. This means the particles around it in the solution will have more area to work on, so there'll be more frequent collisions

Catalysts also help speed up reactions:

- A catalyst is a substance which speeds up a reaction, without being changed or used up in the reaction

- A solid catalyst works by giving the particles a surface to stick to. This increases the number of successful collisions