Physical and chemical changes Cambridge IGCSE Chemistry revision
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In plain words
Melt an ice cube and you still have water: nothing new has been made, and you can freeze it again. That is a physical change. Burn a piece of paper and you get ash and smoke: new substances, and no going back. That is a chemical change.
Three things to know
- A physical change makes no new substance and is usually easy to reverse: melting, boiling, dissolving.
- A chemical change (a reaction) makes one or more new substances and is usually hard to reverse: burning, rusting.
- Signs of a chemical change: a colour change, fizzing (a gas), a solid appearing in a liquid (a precipitate), or the temperature changing.
Tips and tricks
- The test is "has a new substance been made?" If yes, it is a chemical change.
- Dissolving is a physical change: evaporate the water and the solid comes back.
It lands in your notebook with its questions as flashcards.
Physical and chemical changes: 5 questions and answers
These are the quiz’s questions. Do the quiz first, then come back here for the ones that got you.
Which is a chemical change?
Burning makes a new substance, magnesium oxide.
Which is a physical change?
It is still water, and it can be frozen again.
What always happens in a chemical change?
That is what makes it a chemical reaction.
Two colourless solutions are mixed and bubbles of gas appear. What does this suggest?
A gas being formed is a sign that a new substance has been made.
Dissolving sugar in water is which kind of change?
No new substance forms, and the sugar can be recovered.
Quiz
5 questions
Tap an answer and you’ll see straight away whether it’s right, and why.
Worksheet
2 questions, 6 marks. Write your answers on paper, then check them.
Physical and chemical changes
Cambridge IGCSE Chemistry 0620 · 6 marks · papermunch.org
Name ______________________________ Date ______________
State the difference between a physical change and a chemical change.[2]
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A chemical change makes a new substance; a physical change does not (and is usually easily reversed).
Classify each as a physical or a chemical change: ice melting, iron rusting, salt dissolving in water, wood burning.[4]
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Ice melting: physical. Iron rusting: chemical. Salt dissolving: physical. Wood burning: chemical.
Answers: Physical and chemical changes
- 1. A chemical change makes a new substance; a physical change does not (and is usually easily reversed).
- 2. Ice melting: physical. Iron rusting: chemical. Salt dissolving: physical. Wood burning: chemical.