How can you increase the speed of a chemical change?
increase the temperature
Add a catalyst
Increase the concentration of the solution
For gases, increase the pressure
For solids, increase the surface area
For solutions, change the solvent.
If the temperature increases, the molecules speed up. They are more likely to bump into each other and with greater energy, so the reaction occurs faster.
A catalyst increases the rate by lowering the activation energy. More collisions then have enough energy to cause a reaction.
Increasing the concentration of reactants causes collisions that are more frequent. The reaction rate increases.
Increasing the pressure of gaseous reactants increases their concentrations. The collisions are more frequent, so the reaction rate increases.
If a reactant is a solid, grinding it into smaller particles increases its surface area. If there is more surface area on which collisions can occur, the reaction is faster.
If the reaction takes place in solution, it may go faster in a polar solvent than in a nonpolar solvent.