a. CONCENTRATION :
-the higher the concentration, the faster the rate of reaction.
   -because there is a presence of more particles
   - frequent collision speeds up chemical reaction.

b. TEMPERATURE
- the higher the temperature, the faster the reaction.
- the collision is frequent because it possesses kinetic energy

c. SURFACE AREA
 - the greater the surface area, the faster the reaction.

d. CATALYST
- any substance that speeds up chemical reaction without consuming itself
Example :
 Papaya - it fastens the tendering of meat
             - lowers the activation energy.
             - contains catalyst called papain.

e. INHIBITOR
 - substance that slows down chemical reaction
- negative catalyst
- the substance in the applereacts with oxygen in air called oxidation.

* It is dangerous when you fire the tank of gasoline  because the gas molecules  are scattered and oxygen reacted with it so combustion rapidly takes place.