5.1 physical-chemical change
TRANSCRIPT
Dr Pusey
Physical Changes
• Do not create new substances
• Often reversible
• Four main types of physical change
1. Change of state
2. Change of shape
3. Expansion (getting bigger) or contraction (getting smaller)
4. Mixing together, dissolving
Examples
Solid ice melting into a liquid
Wood being chopped up, changing shape
Tablet dissolving in water
Chemical Changes
• Creates new substances
• Often not reversible
• Four main types of chemical change
1. Colour change
2. Making a gas – see bubbles, smell
3. Making a new solid (sometimes called a precipitate)
4. Releasing or absorbing energy
Examples
Fireworks releasing heat and light energy
A nail getting rusty (rust = new solid)