1. (2.3) Chemical Reaction Evidence (p142-143)

2. Chemical Reaction In a chemical reaction new substances are always formed. Can you identify a chemical reaction that you have seen or used today?

3. Evidence of Chemical Reactions When a chemical reaction occurs four types of observations can be made. Can you name some? 1. 2. 3. 4.

4. Evidence of Chemical Reactions – 4 Types 1. ENERGY CHANGE A temperature change (increase or decrease) Light is produced Electricity is produced

5. Evidence of Chemical Reactions – 4 Types 2. GAS IS FORMED Bubbles form in a liquid Presence of an odour

6. Evidence of Chemical Reactions – 4 Types 3. SOLID IS PRODUCED Clear solutions when mixed form a cloudy mixture that contains a solid called a precipitate

7. Evidence of Chemical Reactions – 4 Types 4. CHANGE IN COLOUR In some chemical reactions the colour of the products is different from the colour of the reactants.

8. CLASSWORK Activity 2.10 (p143) Complete and hand in BLM 2-33