AQA · GCSE · Chemistry
Course version: 8462 · Version from Sept 2018
Acids react with some metals to produce salts and hydrogen.
Full specification wording
Reactions of acids with metals: Acids react with some metals to produce salts and hydrogen.
When an acid reacts with a reactive metal, the metal atoms lose electrons and hydrogen ions in the acid gain electrons, producing hydrogen gas.
Checked against the AQA 8462 specification (opens in a new tab) on .
- Point 1 of 2
- 4 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
When an acid reacts with a reactive metal, the metal atoms lose electrons and hydrogen ions in the acid gain electrons, producing hydrogen gas. The other product is a salt formed from the metal ion and the acid's negative ion. For example, magnesium reacts with hydrochloric acid to give magnesium chloride and hydrogen: Mg(s) + 2HCl(aq) → MgCl₂(aq) + H₂(g). The salt name depends on the acid: hydrochloric acid gives chlorides, sulfuric acid gives sulfates. Not all metals react; those below hydrogen in the reactivity series, such as copper, do not react with dilute acids. The reaction is observed as effervescence as hydrogen bubbles form, and the metal gradually dissolves. Testing the gas with a lit splint gives a squeaky pop, confirming hydrogen.
What earns the marks
- Name the salt from the metal and the acid used, for example magnesium sulfate from magnesium and sulfuric acid.
- Write a balanced symbol equation with the correct state symbols where required.
- State that hydrogen gas is produced and describe the test for hydrogen.
- Explain that the metal must be more reactive than hydrogen for the reaction to occur.
- Describe observations such as effervescence and the metal dissolving.
Common mistakes and how to put them right
Naming the salt from the acid only, for example calling the product 'hydrochloric acid salt'.
Put it right: Combine the metal name with the acid-derived ending, such as magnesium chloride.
Writing an unbalanced equation such as Mg + HCl → MgCl₂ + H₂.
Put it right: Balance to Mg + 2HCl → MgCl₂ + H₂.
Claiming all metals react with acids.
Put it right: Metals below hydrogen in the reactivity series, such as copper, do not react with dilute acids.
Exam tips
- Write the word equation first to fix the salt name, then convert to a balanced symbol equation.
- Include state symbols when the question asks for a full equation.
- Link the squeaky pop test directly to hydrogen rather than to oxygen or carbon dioxide.
Try the lesson
The start of the Reactions of acids with metals: Acids react with some metals to produce salts and hydrogen. lesson, made from checked teaching notes for this specification point.
Have a go first
Magnesium ribbon is added to dilute hydrochloric acid. Which two products are formed in this reaction?
Listen
When an acid reacts with a reactive metal, the metal atoms lose electrons and hydrogen ions in the acid gain electrons, producing hydrogen gas. The other product is a salt formed from the metal ion and the acid's negative ion. For example, magnesium reacts with hydrochloric acid to give magnesium chloride and hydrogen: Mg(s) + 2HCl(aq) → MgCl₂(aq) + H₂(g). The salt name depends on the acid: hydrochloric acid gives chlorides, sulfuric acid gives sulfates. Not all metals react; those below hydrogen in the reactivity series, such as copper, do not react with dilute acids. The reaction is observed as effervescence as hydrogen bubbles form, and the metal gradually dissolves. Testing the gas with a lit splint gives a squeaky pop, confirming hydrogen. A strong answer earns marks for these points. Name the salt from the metal and the acid used, for example magnesium sulfate from magnesium and sulfuric acid. Write a balanced symbol equation with the correct state symbols where required. State that hydrogen gas is produced and describe the test for hydrogen. Explain that the metal must be more reactive than hydrogen for the reaction to occur. A common slip: Naming the salt from the acid only, for example calling the product 'hydrochloric acid salt'. Instead, combine the metal name with the acid-derived ending, such as magnesium chloride. Exam tip: Write the word equation first to fix the salt name, then convert to a balanced symbol equation.
See it
Key words
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Acid reactions
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Salt formation
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Hydrogen production
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Reactivity series
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See every definition
- Acid reactions
- Reactions in which acids react with some metals to produce salts and hydrogen.
- Salt formation
- The other product of the reaction, formed from the metal ion and the acid's negative ion.
- Hydrogen production
- Hydrogen gas is produced when hydrogen ions in the acid gain electrons, seen as effervescence as bubbles form.
- Reactivity series
- Metals below hydrogen in it, such as copper, do not react with dilute acids.
Label the diagram
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1Box 1
2Box 2
3Box 3
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