Chemical reactions only occur when reacting particles collide with each other with enough energy to react. There are four important factors, which affect the rate of reaction: Temperature .
Surface area .
Temperature of the reactants.
The lower the temperature in a cold reaction mixture, the slower the particles move. There would also be less collision with less energy.
The higher the temperature in a hot/warm reaction mixture, the faster the particles move. Therefore, the reaction would take less time if using heating (Bunsen burner). There would also be more collision with the greater energy.
Concentration of the dissolved reactants.
The fewer particles in a given area, the less chance of collision with less energy, which makes the reaction slower. The more particles in a given area, the more chance of collision with a greater energy, which makes the reaction faster.
Surface area of solid reactants.
Larger particles would have a smaller surface area in relation to their volume. This means less collision. Small particles have a larger surface area in a relation to their volume. The bigger the surface area the faster the reaction. This means more collision.
Using a catalyst .
Catalyst is something that helps to speed up the rates of the reactions but does not take parts in the reaction. It can be used over and over again so it could increase the rate of conversion of reactants into products. Catalysts are like a barrier, which makes a particle stop from getting away. So the barrier would hold the particle, which makes the other particles collide to it, therefore it would make the reaction faster. Also catalysts are specific i.e. different reaction need different catalysts. Catalysts increase the rate of a reaction by helping break chemical bonds in reactant molecules.
A reversible reaction is a chemical in which the products can be converted back to reactants.