Pearson Edexcel International GCSE in Chemistry · 4CH1 · Free · no account needed
Hydrogen Ions and Neutralisation — exam questions
12 original Incandio exam-style questions on Hydrogen Ions and Neutralisation, 26 marks, about 26 minutes of writing. Each one carries the command word, the tariff and the specification statement it assesses, exactly as a paper presents them. This is an original Incandio practice question, written to reflect the structure and demands of the qualification. It is not an official Pearson Edexcel past-paper question.
This is the practice set for Hydrogen Ions and Neutralisation — the lesson that teaches it. Read the lesson first if the idea is new; come here when you want to find out whether you can turn it into marks. Completely free, no account needed to read.
What these questions ask of you
7 command words run through this set, and on Pearson Edexcel International GCSE Chemistry each one means something precise. Answering the wrong command is the commonest way a candidate who understands the lesson still loses the mark.
- Which (1 mark)
- one option chosen from the set given
- State what is meant by (1–2 marks)
- the definition
- Give (1–2 marks)
- a short factual answer — the most common chemistry command
- Write (1–3 marks)
- the equation, formula or ionic equation, balanced, with state symbols where asked
- Explain (2–4 marks)
- the reason, in terms of particles, bonding, energy or equilibrium Misread as: describing the observation without giving the chemistry that causes it
- Suggest (1–3 marks)
- a plausible answer applying taught chemistry to an unfamiliar substance
- Describe (2–5 marks)
- developed, linked statements of what happens or what is observed Misread as: giving one bare observation where the tariff asked for a developed account
Assessed on Paper 1 (4CH1/1C) and Paper 2 (4CH1/2C), against AO1, AO2, AO3.
Where these sit in the specification
Pearson Edexcel International GCSE Chemistry (4CH1) — statements 2.31 · 2.32. Incandio is aligned to this specification; it is not published by, endorsed by or affiliated with Pearson, and it reproduces none of Pearson's wording.
The 12 questions
Answer them on paper, then open the lesson's exam practice to have them marked. The mark scheme, the accepted and rejected answers and the annotated model answer are in Incandio and are not printed here — an answer beside its question is not practice.
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A student put 25 cm³ of dilute sodium hydroxide solution in a beaker with a pH probe in it, and added dilute hydrochloric acid a little at a time, stirring throughout. She recorded the pH after each addition.
Table 1 — pH as acid was added Acid added / cm³ 0 10 20 25 30 40 pH 13.0 12.8 12.2 7.0 1.9 1.5 (a)
(1)Give
Give the volume of acid at which the solution was exactly neutral.
A student put 25 cm³ of dilute sodium hydroxide solution in a beaker with a pH probe in it, and added dilute hydrochloric acid a little at a time, stirring throughout. She recorded the pH after each addition.
Table 1 — pH as acid was added Acid added / cm³ 0 10 20 25 30 40 pH 13.0 12.8 12.2 7.0 1.9 1.5 volume of acid = ............................ cm3
(b)
(2)Describe
Describe how the pH changes over the whole of Table 1.
A student put 25 cm³ of dilute sodium hydroxide solution in a beaker with a pH probe in it, and added dilute hydrochloric acid a little at a time, stirring throughout. She recorded the pH after each addition.
Table 1 — pH as acid was added Acid added / cm³ 0 10 20 25 30 40 pH 13.0 12.8 12.2 7.0 1.9 1.5 (c)
(3)Explain
Explain what has happened to the hydroxide ions by the time 25 cm³ of acid has been added.
A student put 25 cm³ of dilute sodium hydroxide solution in a beaker with a pH probe in it, and added dilute hydrochloric acid a little at a time, stirring throughout. She recorded the pH after each addition.
Table 1 — pH as acid was added Acid added / cm³ 0 10 20 25 30 40 pH 13.0 12.8 12.2 7.0 1.9 1.5 (d)
(3)Suggest
Suggest why the student would have found the exact neutral point hard to catch had she added the acid in 10 cm³ portions.
A student put 25 cm³ of dilute sodium hydroxide solution in a beaker with a pH probe in it, and added dilute hydrochloric acid a little at a time, stirring throughout. She recorded the pH after each addition.
Table 1 — pH as acid was added Acid added / cm³ 0 10 20 25 30 40 pH 13.0 12.8 12.2 7.0 1.9 1.5 (Total for Question 1 = 9 marks)
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(1)Which
Which ion is produced by all acids in aqueous solution?
Ion A OH⁻ B H⁺ C Cl⁻ D Na⁺ (Total for Question 2 = 1 mark)
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(1)State what is meant by
State what is meant by an alkali.
(Total for Question 3 = 1 mark)
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(1)Give
Give the formula of the substance always formed when an acid neutralises an alkali.
(Total for Question 4 = 1 mark)
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(2)Write
Write the ionic equation for the neutralisation of an acid by an alkali.
(Total for Question 5 = 2 marks)
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(3)Explain
Explain why dry hydrogen chloride gas has no effect on dry litmus paper, but turns damp litmus paper red.
(Total for Question 6 = 3 marks)
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(2)Explain
Explain why the pH of an alkali falls as acid is added to it.
(Total for Question 7 = 2 marks)
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(3)Suggest
Suggest why hydrochloric acid conducts electricity but pure liquid hydrogen chloride does not.
(Total for Question 8 = 3 marks)
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(4)Explain
Explain why the same ionic equation describes the neutralisation of nitric acid by potassium hydroxide and of sulfuric acid by sodium hydroxide.
(Total for Question 9 = 4 marks)
Have them marked, then defend the answer
Practice tells you the mark; teaching it back tells you whether you understand it. On Incandio a topic counts as mastered only once you have taught it and defended it.
- Mark these questions — 12 questions, marked on Incandio against the authored scheme, with the mistake you actually made named.
- Teach it — explain Hydrogen Ions and Neutralisation to Ember, an AI pupil who does not have it yet and asks the awkward question.
- Defend it — argue it against Svante Arrhenius over three rounds, marked against descriptors you can read first.
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Back to the lesson
- Hydrogen Ions and Neutralisation — What every acid has in common, what every alkali has in common, and why every neutralisation is one equation.
- All of Incandio Chemistry · Incandio Exam Practice