AQA · GCSE · Combined Science
Course version: 8464 · Version from Sept 2018
Neutralisation of acids and salt production: the acid used (hydrochloric acid produces chlorides, nitric acid produces nitrates, sulfuric acid produces sulfates)
When an acid reacts with a base, alkali or carbonate, the salt formed depends on which acid is used.
- 3 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
When an acid reacts with a base, alkali or carbonate, the salt formed depends on which acid is used. Hydrochloric acid supplies chloride ions, so its salts are chlorides, such as sodium chloride from sodium hydroxide. Nitric acid supplies nitrate ions, giving nitrates such as potassium nitrate. Sulfuric acid supplies sulfate ions, giving sulfates such as copper(II) sulfate. The metal or ammonium part of the salt comes from the base, alkali or carbonate, while the acid fixes the second part of the salt name. For example, reacting sulfuric acid with copper(II) oxide produces copper(II) sulfate and water. Naming the salt therefore requires identifying both the positive ion from the base, alkali or carbonate and the negative ion from the acid.
What earns the marks
- State that hydrochloric acid produces chloride salts, for example sodium chloride from sodium hydroxide.
- State that nitric acid produces nitrate salts, for example potassium nitrate from potassium hydroxide.
- State that sulfuric acid produces sulfate salts, for example copper(II) sulfate from copper(II) oxide.
- Name a salt by combining the positive ion from the base, alkali or carbonate with the negative ion supplied by the acid.
- Write the salt name correctly, including any Roman numeral where the positive ion has variable charge, such as iron(II) sulfate or iron(III) chloride.
Common mistakes and how to put them right
Naming the salt from the base alone, for example calling the product of hydrochloric acid and sodium hydroxide 'sodium oxide'.
Put it right by naming the positive ion first and the acid-derived negative ion second.
Confusing nitric acid with nitrous acid and writing 'nitrite' salts.
Put it right by linking nitric acid to nitrate salts only.
Omitting the Roman numeral for variable-charge ions, for example writing 'iron chloride' for FeCl₂.
Put it right by writing iron(II) chloride.
Exam tips
- Underline the acid name in the question, then write the negative ion it supplies before naming the salt.
- Check every salt name contains two parts: the positive ion from the base, alkali or carbonate and the negative ion from the acid.
- Practise a three-column table of acid, negative ion and salt ending so the pattern becomes automatic.
Try the lesson
The start of the Neutralisation of acids and salt production: the acid used (hydrochloric acid produces chlorides, nitric acid produces nitrates, sulfuric acid produces sulfates) lesson, made from checked teaching notes for this specification point.
Have a go first
Which salt is produced when nitric acid is neutralised by an alkali?
Listen
When an acid reacts with a base, alkali or carbonate, the salt formed depends on which acid is used. Hydrochloric acid supplies chloride ions, so its salts are chlorides, such as sodium chloride from sodium hydroxide. Nitric acid supplies nitrate ions, giving nitrates such as potassium nitrate. Sulfuric acid supplies sulfate ions, giving sulfates such as copper(II) sulfate. The metal or ammonium part of the salt comes from the base, alkali or carbonate, while the acid fixes the second part of the salt name. For example, reacting sulfuric acid with copper(II) oxide produces copper(II) sulfate and water. Naming the salt therefore requires identifying both the positive ion from the base, alkali or carbonate and the negative ion from the acid. A strong answer earns marks for these points. State that hydrochloric acid produces chloride salts, for example sodium chloride from sodium hydroxide. State that nitric acid produces nitrate salts, for example potassium nitrate from potassium hydroxide. State that sulfuric acid produces sulfate salts, for example copper(II) sulfate from copper(II) oxide. Name a salt by combining the positive ion from the base, alkali or carbonate with the negative ion supplied by the acid. A common slip: Naming the salt from the base alone, for example calling the product of hydrochloric acid and sodium hydroxide 'sodium oxide'. Instead, naming the positive ion first and the acid-derived negative ion second. Exam tip: Underline the acid name in the question, then write the negative ion it supplies before naming the salt.
See it
Key words
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Salt nomenclature
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Ionic composition of acids
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Patterns in chemical reactions
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See every definition
- Salt nomenclature
- Naming the salt requires identifying both the positive ion from the base, alkali or carbonate and the negative ion from the acid.
- Ionic composition of acids
- Hydrochloric acid supplies chloride ions, nitric acid supplies nitrate ions and sulfuric acid supplies sulfate ions.
- Patterns in chemical reactions
- The salt formed depends on which acid is used, while the metal or ammonium part comes from the base, alkali or carbonate.
Label the diagram
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1Box 1
2Box 2
3Box 3
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