3.3

Question 1

Chemical change

Answer 1

Produces new substances with new properties.
Cannot be reversed
Eg. Rust forming on iron, mold on bread, burning paper

Question 2

Physical change

Answer 2

The appearances of substances may change, but no new substances are produced.
The nature of the matter is not changed.
Eg. Chocolate melting, cutting paper in half, dissolving salt in water

Question 3

Exothermic

Answer 3

Releases energy
Eg. Explosion, fire burning, heat is given off
Very hard to reverse process

Question 4

Endothermic

Answer 4

Absorbs energy
Very hard to reverse
Eg. Heat is absorbed, batteries

Question 5

What are some examples of evidence that a chemical change has occurred?

Answer 5

Colour change
Change of temperature 
Sound produced
Gas (bubbles)
Precipitate (solid forming)