AS Chemistry Unit 2 Kinetics

Reaction Rate

For chemicals to react the particles must COLLIDE. Collision must be in the correct ORIENTATION and the energy supply should be sufficient - ACTIVATION ENERGY. Activation Energy is the minimum amount of energy needed for a reaction to occur.

The Collision Theory - changing reaction rate.

You can speed up a reaction by doin any of the following :- increase temperature, use a cayalsts, increase concentration of a reactant, increase pressure (GASES ONLY), increase the reaction surface area.

1. Surface Area.

Smaller the particles the faster the reaction. With small particles there is a greater surface area over which the reaction can take place. Size of particles:- LUMP large particle, RIBBON medium sized particle & POWDER smallest particle.

2. Concentration.

Increasing the concentration of a reactant gives a faster reaction. Increasing the concentration leads to more frequent collisions between particles and therefore an increase in reaction rate.

3. Pressure.

Increasing pressure leads to a faster reaction. There are more frequent collisions between the particles beacuse they are close together and therefore there is more chance fo a reaction happening.

4. Temperature

5. Catalysts

A catalysts is a substance that alters the rate or reaction but remains chemically unchanged. A catalysts speeds up a reaction by providing an alternate reaction pathway of lower activation energy