For a chemical to take place, the particles must with enough energy and the right orientation to break the holding them together. Then the can rearrange themselves into new compounds.

Temperature is a measure of the energy that the particles have. The more heat energy particles have, the they move. This means that are more likely to have enough energy to break the in the reactants, so there will be more successful collisions per .

the concentration increases the rate of the . Because there are more in the same space, there will be more collisions just because they're crowded together more. Because there are more collisions, the of the reaction will be faster.

Decreasing the particle size the rate of the reaction. chunks have a small surface area so react only slowly, because only those particles on the outside are available for . Smaller pieces and powder have a surface area (for the same amount of reactant), and so more particles are available for collisions. Because more particles are available, there will be more collisions per second and therefore the rate of the will increase.