Physical and Chemical Changes

Physical and Chemical Changes

Chapter 1.1: Physical and Chemical Changes

• Starter Activity:

  • Choose a row, column, or diagonal of 3 pictures.

  • Select one of the 3 pictures and decide which is the odd one out, providing a reason for the choice.

Grouping Activity

• Group items into two categories (not specified what items).

Identifying Chemical Change

• Question: Which of these is a chemical change? Why?

• Instruction: Write ideas in notebooks.

Physical or Chemical?

• Learning Objective (LO): Work out the difference between a physical and a chemical change.

Homework

• Give three examples of physical and chemical changes in everyday life.

• Explain why the changes are physical or chemical.

Definitions

• What's the definition of a physical change?

• What's the definition of a chemical change?

Ice Cube Example

• Is an ice cube melting a physical or a chemical change?

Burning Magnesium

• If you burn Magnesium, will there be a physical or a chemical change?

Indicators of a Chemical Reaction

• How to know if a chemical reaction has taken place:

  1. It will change color.

  2. The temperature will change.

  3. It fizzes, meaning a gas is given off.

  4. There might be a different smell.

Chemical Reactions and New Substances

• Adding two substances together can sometimes result in a chemical reaction, where a new substance is made.

• It is very difficult to reverse the reaction and get the original substances back.

• Signs of a chemical reaction:

  • Change in color

  • Heat being given off

  • Bubbles of gas being made

Burning a Candle

• Burning a candle involves both physical and chemical changes.

Burning a Candle - Physical vs. Chemical

• What is the physical change?

• What is the chemical change?

Burning a Candle - Gas

• When a candle burns, what gas is given off?

• What does this mean?

Burning a Candle - Chemical Equation

• Burning a candle involves the following chemical reactions:

  • Carbon + Oxygen $\rightarrow$ Carbon Dioxide

  • Hydrogen + Oxygen $\rightarrow$ Water

Examples of Changes

• Chemical Reactions (✓):

  • Adding acid to alkali

  • Fireworks

  • Driving a car

  • Frying an egg

  • Burning a candle

  • Baking a cake

  • Launching a space rocket

  • Lighting a match

• Physical Changes (x):

  • Ice cream melting

  • Boiling the kettle

  • Melting candle wax

  • Dissolving sugar in tea

  • Making ice cubes

  • Ironing clothes

  • Printing

• Physical changes are changes that are not chemical changes.