Pearson Edexcel International GCSE in Chemistry · 4CH1 · Free · no account needed
Concentration and Gas Volumes — exam questions
11 original Incandio exam-style questions on Concentration and Gas Volumes, 25 marks, about 25 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 Concentration and Gas Volumes — 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
5 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
- Calculate (1–4 marks)
- a numerical answer with working, to the stated precision
- 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
- Determine (1–4 marks)
- a value reached by combining given data with a method the learner selects
- Suggest (1–3 marks)
- a plausible answer applying taught chemistry to an unfamiliar substance
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 1.34 · 1.35. 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 11 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.
-
A student added 0.100 mol/dm³ hydrochloric acid from a burette to 25.0 cm³ of sodium hydroxide solution of unknown concentration. The acid required was 22.0 cm³. The equation is HCl + NaOH → NaCl + H₂O.
Relative atomic masses — H = 1, C = 12, O = 16, Na = 23, Mg = 24, S = 32, Cl = 35.5
(a)
(2)Calculate
Calculate the number of moles of hydrochloric acid added from the burette.
A student added 0.100 mol/dm³ hydrochloric acid from a burette to 25.0 cm³ of sodium hydroxide solution of unknown concentration. The acid required was 22.0 cm³. The equation is HCl + NaOH → NaCl + H₂O.
Relative atomic masses — H = 1, C = 12, O = 16, Na = 23, Mg = 24, S = 32, Cl = 35.5
............................ mol
(b)
(1)Determine
Determine the number of moles of sodium hydroxide in the flask.
A student added 0.100 mol/dm³ hydrochloric acid from a burette to 25.0 cm³ of sodium hydroxide solution of unknown concentration. The acid required was 22.0 cm³. The equation is HCl + NaOH → NaCl + H₂O.
Relative atomic masses — H = 1, C = 12, O = 16, Na = 23, Mg = 24, S = 32, Cl = 35.5
(c)
(3)Determine
Determine the mass of sodium hydroxide dissolved in each cubic decimetre of the solution.
A student added 0.100 mol/dm³ hydrochloric acid from a burette to 25.0 cm³ of sodium hydroxide solution of unknown concentration. The acid required was 22.0 cm³. The equation is HCl + NaOH → NaCl + H₂O.
Relative atomic masses — H = 1, C = 12, O = 16, Na = 23, Mg = 24, S = 32, Cl = 35.5
mass of sodium hydroxide dissolved = ............................ g/dm3
(d)
(3)Suggest
The student read the burette while it was tilted towards her, so every reading was slightly too low. Suggest the effect of this on the calculated concentration of the sodium hydroxide.
A student added 0.100 mol/dm³ hydrochloric acid from a burette to 25.0 cm³ of sodium hydroxide solution of unknown concentration. The acid required was 22.0 cm³. The equation is HCl + NaOH → NaCl + H₂O.
Relative atomic masses — H = 1, C = 12, O = 16, Na = 23, Mg = 24, S = 32, Cl = 35.5
(Total for Question 1 = 9 marks)
-
(1)Which
Which volume is equal to 250 cm³?
Volume A 0.025 dm³ B 0.250 dm³ C 2.50 dm³ D 250 000 dm³ (Total for Question 2 = 1 mark)
-
(1)Calculate
Calculate the volume occupied by 0.25 moles of carbon dioxide at room temperature and pressure.
Molar volume — One mole of any gas occupies 24 dm³ at room temperature and pressure.
volume occupied by 0 = ............................ dm3
(Total for Question 3 = 1 mark)
-
(2)Calculate
Calculate the concentration, in mol/dm³, of a solution containing 0.050 moles of solute in 500 cm³ of solution.
concentration = ............................ mol/dm3
(Total for Question 4 = 2 marks)
-
(3)Calculate
Calculate the mass of sodium hydroxide, NaOH, needed to make 250 cm³ of a 0.200 mol/dm³ solution.
Relative atomic masses — H = 1, C = 12, O = 16, Na = 23, Mg = 24, S = 32, Cl = 35.5
mass of sodium hydroxide = ............................ g
(Total for Question 5 = 3 marks)
-
(3)Calculate
Calculate the volume of hydrogen produced when 0.48 g of magnesium reacts completely with excess hydrochloric acid. The equation is Mg + 2HCl → MgCl₂ + H₂.
Relative atomic masses — H = 1, C = 12, O = 16, Na = 23, Mg = 24, S = 32, Cl = 35.5
Molar volume — One mole of any gas occupies 24 dm³ at room temperature and pressure.
volume of hydrogen produced = ............................ dm3
(Total for Question 6 = 3 marks)
-
(2)Explain
Explain why equal volumes of two different gases contain the same number of molecules at the same temperature and pressure.
(Total for Question 7 = 2 marks)
-
(4)Calculate
Calculate the volume of carbon dioxide, at room temperature and pressure, produced when 2.50 g of calcium carbonate reacts completely with excess hydrochloric acid. The equation is CaCO₃ + 2HCl → CaCl₂ + H₂O + CO₂.
Given — One mole of any gas occupies 24 dm³ at room temperature and pressure. Relative atomic masses: C = 12, O = 16, Ca = 40.
volume of carbon dioxide = ............................ dm³
(Total for Question 8 = 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 — 11 questions, marked on Incandio against the authored scheme, with the mistake you actually made named.
- Teach it — explain Concentration and Gas Volumes 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.
Completely free. No subscriptions, no paywalls, no account needed to start.
Back to the lesson
- Concentration and Gas Volumes — Counting particles in a solution you can only measure by volume, and in a gas you cannot weigh at all.
- All of Incandio Chemistry · Incandio Exam Practice