BREAKING
Mole Day revealed to be a lie, chemists demand refund★Student titrates to pale pink, class gives standing ovation★Bunsen left on yellow flame, teacher sighs for 3rd week★
  1. Home
  2. A Level
  3. Chemistry
  4. OCR
  5. Determining orders of reaction

OCR A Level Chemistry

Topic questions The rate and extent of chemical change Determining orders of reaction

Determining orders of reaction

11 questions · 78 marks · about 1.5 hours

Determining orders of reaction questions

TopicDetermining orders of reaction

OCR H432 Determining orders of reaction 11 questions

Periodic table, elements and physical chemistry June 2025, Question 18 14 marks

Nitrogen monoxide, NO, reacts with oxygen to form nitrogen dioxide, NO2.

Question 18, shown as an image
(a)

The rate of reaction increases in the presence of a heterogeneous platinum catalyst.

(a)(i)

Explain why platinum is an example of a heterogeneous catalyst for Reaction 18.1.

[1]
Reveal mark scheme Mark scheme for question 18(a)(i)
(a)(ii)

Explain how the platinum catalyst increases the rate of reaction.

Include a labelled sketch of the Boltzmann distribution on the grid.

Figure for question 18
[2]
Reveal mark scheme Mark scheme for question 18(a)(ii)
(a)(iii)

In industry, catalysts have great economic importance and benefits for increased sustainability.

Explain how the use of catalysts is beneficial to the environment.

[1]
Reveal mark scheme Mark scheme for question 18(a)(iii)
(b)

The following data was obtained in a series of experiments on the rate of the reaction for Reaction 18.1 at a constant temperature.

Experiment[NO] / mol dm–3[O2] / mol dm–3rate / mol dm–3 s–1
10.0400.0357.45 × 10– 4
20.0400.0701.49 × 10–3
30.0600.0351.68 × 10–3

Determine the orders with respect to NO and O2. Explain your reasoning.

Determine the rate equation and calculate the rate constant, k, including units.

[5]
Reveal mark scheme Mark scheme for question 18(b)
(c)
Figure for question 18
(c)(i)

Complete the table by adding the missing value of ln k.

[1]
Reveal mark scheme Mark scheme for question 18(c)(i)
(c)(ii)
Figure for question 18 Figure for question 18 Figure for question 18
[4]
Reveal mark scheme Mark scheme for question 18(c)(ii)

Periodic table, elements and physical chemistry June 2024, Question 17 7 marks

Figure for question 17
(a)

Using collision theory, explain why the gradient decreases over time.

[1]
Reveal mark scheme Mark scheme for question 17(a)
(b)

* Use the graph to determine the order of reaction with respect to CV, the rate of the reaction at three minutes and the rate constant, k.

Your answer must show full working on the graph and on the lines below.

[6]
Reveal mark scheme Mark scheme for question 17(b)

Periodic table, elements and physical chemistry June 2023, Question 7 1 mark

The reaction below is first order with respect to reactant X.

Question 7, shown as an image

When the initial concentration of X is 1.0 mol dm–3, the half-life is 16 minutes.

What is the half-life when the initial concentration of X is 2.0 mol dm–3?

A 2 minutes

B 4 minutes

C 8 minutes

D 16 minutes

Your answer

[1]
Reveal mark scheme Mark scheme for question 7

Periodic table, elements and physical chemistry June 2022, Question 16 10 marks

A catalytic converter in a car removes nitrogen monoxide, NO, and carbon monoxide, CO, from the exhaust gases.

(a)

One reaction that happens in a catalytic converter is shown below.

Question 16, shown as an image
(a)(i)

Explain how increasing the temperature increases the rate of Reaction 16.1.

Include a labelled sketch, using Boltzmann distributions, on the grid below.

Label the axes.

[3]
Reveal mark scheme Mark scheme for question 16(a)(i)
(a)(ii)
Figure for question 16
[5]
Reveal mark scheme Mark scheme for question 16(a)(ii)
(b)

Carbon monoxide also reacts with nitrogen dioxide as shown in Reaction 16.2.

Question 16, shown as an image

The rate equation for Reaction 16.2 is shown below:

rate = k [NO2(g)]2

Suggest a possible two-step mechanism for Reaction 16.2. The first step is much slower than the second step.

[2]
Reveal mark scheme Mark scheme for question 16(b)

Periodic table, elements and physical chemistry November 2021, Question 21 10 marks

This question is about how the rate of reaction is affected by changes in conditions.

A student carries out two investigations using the reaction between aqueous thiosulfate ions, S2O32–(aq), and aqueous hydrogen ions, H+(aq). Reaction 21.1 S2O32–(aq) + 2H+(aq) → S(s) + SO2(g) + H2O(l)

(a)
Figure for question 21
(a)(i)

Explain how the student’s results support this rate equation.

[2]
Reveal mark scheme Mark scheme for question 21(a)(i)
(a)(ii)

Predict a possible two-step mechanism for Reaction 21.1. The first step is the rate-determining step.

Step 1........

Step 2........

[2]
Reveal mark scheme Mark scheme for question 21(a)(ii)
(b)
Figure for question 21
(b)(i)

Calculate the activation energy, Ea, for Reaction 21.1, in kJ mol–1.

Give your answer to 3 significant figures.

Ea =........ kJ mol–1

[3]
Reveal mark scheme Mark scheme for question 21(b)(i)
(b)(ii)

From the graph the student estimates the value of ln A as –2.00. (A is the pre-exponential factor.)

Explain what mistake the student has made.

[1]
Reveal mark scheme Mark scheme for question 21(b)(ii)
(b)(iii)
Figure for question 21 Figure for question 21
[2]
Reveal mark scheme Mark scheme for question 21(b)(iii)

Periodic table, elements and physical chemistry June 2018, Question 17 11 marks

Figure for question 17
(a)

* Determine the rate constant and a possible two-step mechanism for this reaction that are

consistent with these results.

[6]
Reveal mark scheme Mark scheme for question 17(a)
(b)

A student carries out an investigation to find the activation energy, Ea, and the pre-exponential factor, A, of a reaction.

The student determines the rate constant, k, at different temperatures, T. The student then plots a graph of ln k against 1 / T as shown below.

Figure for question 17
(b)(i)

Draw a best-fit straight line and calculate the activation energy, in J mol–1. Give your answer to three significant figures.

Show your working.

activation energy, Ea = +........ J mol–1

[3]
Reveal mark scheme Mark scheme for question 17(b)(i)
(b)(ii)

Use the graph to calculate the value of the pre-exponential factor, A.

Show your working.

[2]
Reveal mark scheme Mark scheme for question 17(b)(ii)

Report a problem with a question on this page
What is wrong?

Goes to whoever maintains the question split. No account needed and nothing is published on this page.

Memes

Certified Chemistry memes. Peer-reviewed by nobody.

Laugh now. Cry in the exam hall later. Then come back and do a past paper.

Do the mole calculation
Write ‘exothermic’ and pray
Me on the 6-marker about electrolysis
Knowing water is H₂O
Balancing an equation first try
Getting two concordant titres
Realising nobody actually knows what a mole is
Chemistry enlightenment, ranked

Mum 💖

how's chemistry going love?? 🥰

we're doing bonding rn

aww that's lovely 💕

📱 Screen time this week · TikTok6h 2m

Zero bonds were formed

Chemistry starter pack

Goggles that fog instantlyBunsen on the orange flameBurette that's always leakingThis website
Goggles on, collect all four