GCSE Chemistry · Edexcel 1CH0 · Topic 3B
Making salts
Key points
- Acid + metal → salt + hydrogen. Acid + metal oxide or hydroxide → salt + water. Acid + metal carbonate → salt + water + carbon dioxide.
- The acid gives the salt's name: hydrochloric → chloride, sulfuric → sulfate, nitric → nitrate.
- Tests: hydrogen gives a squeaky pop with a lighted splint; carbon dioxide turns limewater milky.
- Core practical: make a soluble salt (e.g. copper sulfate) by adding excess insoluble base to warm acid, filtering off the excess, then crystallising.
- Use titration to make a salt from an acid and a soluble alkali in exact amounts.
- Solubility rules: all sodium, potassium, ammonium and nitrate salts are soluble; most chlorides are soluble (not silver, lead); most sulfates are soluble (not barium, lead, calcium); most carbonates and hydroxides are insoluble (except sodium, potassium, ammonium).
- Insoluble salts are made by precipitation: mix two solutions, filter, wash and dry.
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Salts are ionic compounds made when the hydrogen in an acid is replaced by a metal or ammonium ion. These notes cover the reactions of acids, naming salts, gas tests, the solubility rules and the three ways of preparing a salt, including…
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