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SingaporeCombined Science

Chemistry: Reactions, Acids and Salts

3 dot points across 3 inquiry questions. Click any dot point for a focused answer with worked past exam questions where available.

What makes a substance acidic or alkaline, and how do acids react with other substances?

Describe the properties of acids and bases, use the pH scale and indicators, and write the products of acid reactions with metals, bases and carbonates
A focused N(A)-Level answer on acids and bases. Properties of acids and alkalis, the pH scale and indicators, and the three key reactions of acids with metals, bases and carbonates.
8 min answer →

How do we know a chemical reaction has happened, and why do some reactions give out heat while others take it in?

Recognise the signs of a chemical reaction, balance simple word and symbol equations, and classify reactions as exothermic or endothermic
A focused N(A)-Level answer on reactions. The signs of a chemical change, conservation of mass, balancing simple equations, and telling exothermic from endothermic reactions.
8 min answer →

What is a salt, and how do we make a pure, dry sample of one in the laboratory?

Describe what a salt is, distinguish soluble and insoluble salts, and outline the preparation of a soluble salt from an acid and an insoluble base
A focused N(A)-Level answer on salts. What a salt is, soluble and insoluble salts, and the step-by-step preparation of a pure dry soluble salt from an acid and an insoluble base.
8 min answer →