Pearson Edexcel International GCSE in Chemistry · 4CH1 · Free · no account needed
Titrations — exam questions
9 original Incandio exam-style questions on titrations, 19 marks, about 19 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 Titrations — 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
6 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.
- Give (1–2 marks)
- a short factual answer — the most common chemistry command
- 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
- Calculate (1–4 marks)
- a numerical answer with working, to the stated precision
- Determine (1–4 marks)
- a value reached by combining given data with a method the learner selects
- 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 2.40 · 2.33. 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 9 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 used 0.100 mol dm⁻³ sodium hydroxide solution to find the concentration of a hydrochloric acid. She pipetted 25.0 cm³ of the acid into a conical flask, added a few drops of indicator, and titrated with the sodium hydroxide from a burette.
Table 1 — the student's burette readings. Rough 1 2 3 Final reading / cm³ 23.10 45.55 22.40 44.85 Initial reading / cm³ 0.00 23.10 0.05 22.40 Titre / cm³ 23.10 22.45 22.35 22.45 Equation — HCl(aq) + NaOH(aq) → NaCl(aq) + H₂O(l)
(a)
(2)Calculate
Calculate the mean titre the student should use, using Table 1.
A student used 0.100 mol dm⁻³ sodium hydroxide solution to find the concentration of a hydrochloric acid. She pipetted 25.0 cm³ of the acid into a conical flask, added a few drops of indicator, and titrated with the sodium hydroxide from a burette.
Table 1 — the student's burette readings. Rough 1 2 3 Final reading / cm³ 23.10 45.55 22.40 44.85 Initial reading / cm³ 0.00 23.10 0.05 22.40 Titre / cm³ 23.10 22.45 22.35 22.45 Equation — HCl(aq) + NaOH(aq) → NaCl(aq) + H₂O(l)
............................ cm³
(b)
(2)Calculate
Calculate the number of moles of sodium hydroxide in the mean titre.
A student used 0.100 mol dm⁻³ sodium hydroxide solution to find the concentration of a hydrochloric acid. She pipetted 25.0 cm³ of the acid into a conical flask, added a few drops of indicator, and titrated with the sodium hydroxide from a burette.
Table 1 — the student's burette readings. Rough 1 2 3 Final reading / cm³ 23.10 45.55 22.40 44.85 Initial reading / cm³ 0.00 23.10 0.05 22.40 Titre / cm³ 23.10 22.45 22.35 22.45 Equation — HCl(aq) + NaOH(aq) → NaCl(aq) + H₂O(l)
(c)
(1)Determine
Determine the number of moles of hydrochloric acid in the 25.0 cm³ sample.
A student used 0.100 mol dm⁻³ sodium hydroxide solution to find the concentration of a hydrochloric acid. She pipetted 25.0 cm³ of the acid into a conical flask, added a few drops of indicator, and titrated with the sodium hydroxide from a burette.
Table 1 — the student's burette readings. Rough 1 2 3 Final reading / cm³ 23.10 45.55 22.40 44.85 Initial reading / cm³ 0.00 23.10 0.05 22.40 Titre / cm³ 23.10 22.45 22.35 22.45 Equation — HCl(aq) + NaOH(aq) → NaCl(aq) + H₂O(l)
(d)
(3)Calculate
Calculate the concentration of the hydrochloric acid in mol dm⁻³. Give your answer to 3 significant figures.
A student used 0.100 mol dm⁻³ sodium hydroxide solution to find the concentration of a hydrochloric acid. She pipetted 25.0 cm³ of the acid into a conical flask, added a few drops of indicator, and titrated with the sodium hydroxide from a burette.
Table 1 — the student's burette readings. Rough 1 2 3 Final reading / cm³ 23.10 45.55 22.40 44.85 Initial reading / cm³ 0.00 23.10 0.05 22.40 Titre / cm³ 23.10 22.45 22.35 22.45 Equation — HCl(aq) + NaOH(aq) → NaCl(aq) + H₂O(l)
(Total for Question 1 = 8 marks)
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(1)Give
Give the name of the piece of apparatus used to measure the 25.0 cm³ of acid accurately.
(Total for Question 2 = 1 mark)
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(2)Explain
Explain why the rough titre is not included when the mean titre is calculated.
(Total for Question 3 = 2 marks)
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(1)Give
Give a reason why the conical flask is swirled continuously during the titration.
(Total for Question 4 = 1 mark)
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(2)Suggest
A second student rinsed the burette with distilled water and filled it with sodium hydroxide without rinsing it with the alkali first. Suggest what effect this would have on her titre.
(Total for Question 5 = 2 marks)
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(5)Describe
Describe how a titration is carried out to find the volume of acid that exactly neutralises 25.0 cm³ of sodium hydroxide solution.
(Total for Question 6 = 5 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 — 9 questions, marked on Incandio against the authored scheme, with the mistake you actually made named.
- Teach it — explain titrations to Ember, an AI pupil who does not have it yet and asks the awkward question.
- Defend it — argue it against Joseph Louis Gay-Lussac over three rounds, marked against descriptors you can read first.
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Back to the lesson
- Titrations — Finding the exact volume that neutralises — and then making the salt again without the indicator in it.
- All of Incandio Chemistry · Incandio Exam Practice