AQA · GCSE · Combined Science
Course version: 8464 · Version from Sept 2018
Key ideas: proton transfer
Proton transfer is the movement of a hydrogen ion (H⁺) from one substance to another.
Checked against the AQA 8464 specification (opens in a new tab) on .
- Point 17 of 26
- 3 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
Proton transfer is the movement of a hydrogen ion (H⁺) from one substance to another. A hydrogen ion is simply a proton. In chemistry, an acid acts as a proton donor, releasing H⁺ ions in aqueous solution. A base acts as a proton acceptor. When an acid reacts with a base, a proton is transferred.
For example: In neutralisation, the H⁺ ion from the acid transfers to the OH⁻ ion from the alkali to form water: H⁺(aq) + OH⁻(aq) → H₂O(l).
What earns the marks
- Identifies a hydrogen ion (H⁺) as a proton.
- Describes an acid as a proton donor.
- Describes a base as a proton acceptor.
- Explains neutralisation in terms of proton transfer, using the ionic equation H⁺(aq) + OH⁻(aq) → H₂O(l).
Common mistakes and how to put them right
Treating a proton as an electron or a hydrogen atom.
Put it right: A proton is H⁺, a hydrogen atom is H, and an electron is e⁻.
Confusing acids and bases.
Put it right: Acids donate protons (H⁺) and bases accept them.
Writing the neutralisation equation incorrectly.
Put it right: Ensure the charges balance and state symbols are used, H⁺(aq) + OH⁻(aq) → H₂O(l).
Exam tips
- When asked about the ions in acids, state that they produce H⁺ ions, which are protons.
- For neutralisation questions, write the ionic equation H⁺(aq) + OH⁻(aq) → H₂O(l) to show the proton transfer.
Try the lesson
The start of the Key ideas: proton transfer lesson, made from checked teaching notes for this specification point.
Have a go first
In an acid–base reaction, a proton is transferred from an acid to a base. What is a proton in this context?
Listen
Proton transfer is the movement of a hydrogen ion (H⁺) from one substance to another. A hydrogen ion is simply a proton. In chemistry, an acid acts as a proton donor, releasing H⁺ ions in aqueous solution. A base acts as a proton acceptor. When an acid reacts with a base, a proton is transferred. For example, in neutralisation, the H⁺ ion from the acid transfers to the OH⁻ ion from the alkali to form water: H⁺(aq) + OH⁻(aq) → H₂O(l). A strong answer earns marks for these points. Identifies a hydrogen ion (H⁺) as a proton. Describes an acid as a proton donor. Describes a base as a proton acceptor. Explains neutralisation in terms of proton transfer, using the ionic equation H⁺(aq) + OH⁻(aq) → H₂O(l). A common slip: Treating a proton as an electron or a hydrogen atom. Instead, a proton is H⁺, a hydrogen atom is H, and an electron is e⁻. Exam tip: When asked about the ions in acids, state that they produce H⁺ ions, which are protons.
See it
Key words
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Acids as proton donors
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Bases as proton acceptors
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Neutralisation
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See every definition
- Acids as proton donors
- An acid acts as a proton donor, releasing H⁺ ions in aqueous solution.
- Bases as proton acceptors
- A base acts as a proton acceptor.
- Neutralisation
- When an acid reacts with a base, a proton is transferred, and the H⁺ ion from the acid transfers to the OH⁻ ion from the alkali to form water.
Label the diagram
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