Pearson Edexcel International GCSE in Chemistry · 4CH1 · Free · no account needed
Rates of Reaction — exam questions
10 original Incandio exam-style questions on Rates of Reaction, 23 marks, about 23 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 Rates of Reaction — 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.
- 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
- State (1 mark)
- one precise fact, no justification
- 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 3.9 · 3.10 · 3.15. 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 10 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 added 50 cm³ of dilute hydrochloric acid to 5.0 g of marble chips in a flask on a balance, and recorded the loss in mass as carbon dioxide escaped. She repeated the experiment with the same mass of marble powder.
Figure 1 — loss in mass against time for the marble chips. Plotted as a line; the graph is drawn in Incandio and the readings are below. Time / s Loss in mass / g 0 0 20 0.62 40 1.05 60 1.34 90 1.62 120 1.76 150 1.82 180 1.83 (a)
(1)Give
Give the total loss in mass at the end of the reaction, using Figure 1.
A student added 50 cm³ of dilute hydrochloric acid to 5.0 g of marble chips in a flask on a balance, and recorded the loss in mass as carbon dioxide escaped. She repeated the experiment with the same mass of marble powder.
Figure 1 — loss in mass against time for the marble chips. Plotted as a line; the graph is drawn in Incandio and the readings are below. Time / s Loss in mass / g 0 0 20 0.62 40 1.05 60 1.34 90 1.62 120 1.76 150 1.82 180 1.83 total loss = ............................ g
(b)
(2)Describe
Describe how the rate of reaction changes over the 180 seconds shown in Figure 1.
A student added 50 cm³ of dilute hydrochloric acid to 5.0 g of marble chips in a flask on a balance, and recorded the loss in mass as carbon dioxide escaped. She repeated the experiment with the same mass of marble powder.
Figure 1 — loss in mass against time for the marble chips. Plotted as a line; the graph is drawn in Incandio and the readings are below. Time / s Loss in mass / g 0 0 20 0.62 40 1.05 60 1.34 90 1.62 120 1.76 150 1.82 180 1.83 (c)
(3)Explain
Explain, in terms of particles, why the rate changes in the way Figure 1 shows.
A student added 50 cm³ of dilute hydrochloric acid to 5.0 g of marble chips in a flask on a balance, and recorded the loss in mass as carbon dioxide escaped. She repeated the experiment with the same mass of marble powder.
Figure 1 — loss in mass against time for the marble chips. Plotted as a line; the graph is drawn in Incandio and the readings are below. Time / s Loss in mass / g 0 0 20 0.62 40 1.05 60 1.34 90 1.62 120 1.76 150 1.82 180 1.83 (d)
(3)Describe
Describe how the curve for the marble powder would differ from the curve in Figure 1, and give a reason for each difference.
A student added 50 cm³ of dilute hydrochloric acid to 5.0 g of marble chips in a flask on a balance, and recorded the loss in mass as carbon dioxide escaped. She repeated the experiment with the same mass of marble powder.
Figure 1 — loss in mass against time for the marble chips. Plotted as a line; the graph is drawn in Incandio and the readings are below. Time / s Loss in mass / g 0 0 20 0.62 40 1.05 60 1.34 90 1.62 120 1.76 150 1.82 180 1.83 (Total for Question 1 = 9 marks)
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(2)Give
Give two factors, other than temperature, that affect the rate of a chemical reaction.
(Total for Question 2 = 2 marks)
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(3)Explain
Explain why increasing the concentration of the acid increases the rate of reaction.
(Total for Question 3 = 3 marks)
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(4)Explain
Explain why raising the temperature has a greater effect on the rate of reaction than increasing the concentration by the same proportion.
(Total for Question 4 = 4 marks)
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(1)State
State what a catalyst does to the activation energy of a reaction.
(Total for Question 5 = 1 mark)
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(2)Suggest
Flour mills take great care to prevent clouds of flour dust building up in the air. Suggest why.
(Total for Question 6 = 2 marks)
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(2)Explain
Explain why a catalyst can be recovered unchanged at the end of a reaction even though it took part in it.
(Total for Question 7 = 2 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 — 10 questions, marked on Incandio against the authored scheme, with the mistake you actually made named.
- Teach it — explain Rates of Reaction to Ember, an AI pupil who does not have it yet and asks the awkward question.
- Defend it — argue it against Marcellin Berthelot over three rounds, marked against descriptors you can read first.
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Back to the lesson
- Rates of Reaction — Four things that make a reaction faster, and two ways of measuring whether they did.
- All of Incandio Chemistry · Incandio Exam Practice