Chemical reactions

1. Methane is a compound of carbon and ____________.
7. A change that transfers energy to the surroundings.
9. _________fuels, Petrol, diesel and coal are examples.
10. A change where the surroundings transfer energy to substances.
11. Another word for burning.
12. variable described by words or by numbers that can only have certain values.
14. A material that burns to transfer energy by heating

2. In a chemical reaction the substances on the left hand side of the equation
3. A reaction where you can get the reactants back.
4. In these reactions a compound breaks down into simpler compounds or elements
5. _______decomposition; In these reactions a substance breaks down on heating.
6. In these reactions substances react with oxygen.
8. These speed up or slow reactions.
13. In chemical reactions the total mass of the reactants_________the total mass of the products.