State necessary conditions for a chemical reaction to take place.

Necessary conditions for a chemical reaction to take place are:

1. Reactants must combine to form new substances.
2. Also the reactants need to be mixed in solution form as reactants mix in solution form.
3. Some reactions need to be heated to carry the reaction or some reactions, may release energy.
4. Some reactions may need a catalyst to complete the reaction.
5. New substances will be formed after the mixing of reactants.