3.1 Characteristics of chemical reactions

1. The four characteristics of a chemical reaction are:

- reactants change into reaction products; the properties of matter have changed;

- there is always an energy-effect;

- the total mass of the reactants equals the total mass of the reaction products;

- a minimum reaction temperature is needed for a chemical reaction to occur

2. a) In an exothermic reaction energy is released: the reactants lose energy, the environment gains energy.

b) For an endothermic reaction energy is needed. The reactants gain energy, the environment loses energy.

c)The types of energy you will encounter regularly are: heat, electricity and light.

3.

The type of reactants

The surface area (degree of distribution)

The concentration (of the reactants)

The temperature

The presence of a catalyst