1. Science Nine Hantsport School P. Warren
Chemical Changes
Science Nine Hantsport School P. Warren

2. Pure Substances when combined, may undergo a physical or a chemical change

3. Physical Change
A change in matter in which no new type of matter is produced.
Examples:
Freezing --Cutting into pieces
Melting --Ploughing a field
Boiling --Moulding a Sculpture

4. Same Molecular Structure on both sides
Physical Change
Water (Ice) Water (Liquid)
Same Molecular Structure on both sides

5. Chemical Change
One or more new substances are formed in which these new substances have properties different from those of the starting materials
Ex. Rusting of Steel
before rusting after rusting (hard and shiny) (soft and reddish brown)

6. Ethane + Hydrogen  Methane + Methane
Chemical Change
Ethane + Hydrogen  Methane + Methane

7. Clues Indicating Chemical Change
New Colour Appears
Heat or Light is Given Off
Bubbles of Gas are Formed
Solid Material Forms in a Liquid (Precipitate)
The Change is Difficult to Reverse

8. Iron + Oxygen + Water  Rust
Chemical Reactions
A chemical change results from a chemical reaction which involves reactants and products.
Iron Oxygen Water  Rust
Reactants Product
Plus Plus Produces

9. Examples of Chemical Changes
Reactant Products
Hydrogen Peroxide  water + oxygen
Ethane + Hydrogen  Methane + Methane
Reactant(s) are any substance(s) that is used up in a reaction
Product(s) are any substances that is produced in a reaction
Reactants Products

10. Writing Chemical Reactions
Reactant + Reactant  Product + Product
Example:
Copper (II) Sulphate reacts with iron to produce Iron (II) Sulphate and Copper
Copper (II) Sulphate + Iron  Iron (II) Sulphate + Copper
Reactants Products

11. Worksheet