1. Evidence of a Chemical Reaction 3. Energy Changes

2. Experiment 1 Aim:To investigate the burning of magnesium. Method:

3. Results: A bright white light is produced. Conclusion: The silver magnesium metal changes to white powder (new substance formed). This change is accompanied by a bright light (detectable energy change).

4. Experiment 2 Aim: To investigate the reaction between dilute hydrochloric acid and dilute sodium hydroxide. Method: Dilute hydrochloric acid Dilute sodium hydroxide +

5. Results: When touching the test tube, the test tube becomes hot. This change can be measured using a thermometer. Conclusion: No change in appearance, but test tube gets hot. New substance has formed. Achemical reaction has taken place.

6. Exothermic Reaction: This is a reaction which releases (gives out) energy. Combustion and neutralisation are examples of exothermic reactions. Endothermic Reaction: This is a reaction which consumes (takes in) energy. Photosynthesis is an example of an endothermic reaction.