Physical and chemical changes
Answers are for parents and teachers.
1
List three physical changes and three chemical changes from your home.
Answers differ: for example ice melting, sugar dissolving, paper tearing; and toast browning, an egg cooking, a nail rusting.
2
Explain in your own words what happens to atoms in a chemical reaction.
The bonds between atoms in the reactants break and new bonds form; the same atoms are rearranged into new substances.
3
Write the word equation for baking soda reacting with vinegar.
baking soda + vinegar → carbon dioxide + water + sodium acetate.
4
A student sees bubbles in a pot of boiling water. Is it a reaction? Explain.
No: the bubbles are water vapour, so boiling is a physical change.
5
Find the mistake: “Every chemical reaction gives out heat.”
Some reactions absorb heat and make things cooler.