UNIT OVERVIEW

This unit teaches you to tell the difference between physical and chemical changes. You see both types of changes every day. When you boil water for tea, that is different from burning wood at a braai. When you dissolve sugar, that is different from iron rusting.

You will learn:

• How to identify physical and chemical changes using evidence
• How to separate mixtures using physical methods
• How chemical separation breaks bonds and forms new substances
• How atoms and mass are conserved in reactions
• How the law of constant composition works
• How to write and balance chemical equations

Practical connections:

• Water treatment plants use filtration and chlorination to clean water
• Gold mining uses physical separation (crushing) and chemical processes (cyanide leaching)
• Recycling plants separate plastics, metals, and paper using physical properties
• Pharmaceutical companies use constant composition to ensure correct drug doses

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