Oxford Cambridge and RSA
Tuesday 20 May 2025 – Morning
AS Level Chemistry B (Salters)
H033/02 Chemistry in depth
Time allowed: 1 hour 30 minutes
You must have:
* 1 8 4 2 2 6 0 9 2 2 *
• the Data Sheet for Chemistry B
You can use:
• a scientific or graphical calculator
• an HB pencil
* H 0 3 3 0 2 *
Please write clearly in black ink. Do not write in the barcodes.
Centre number Candidate number
First name(s)
Last name
INSTRUCTIONS
• Use black ink. You can use an HB pencil, but only for graphs and diagrams.
• Write your answer to each question in the space provided. If you need extra space use
the lined page at the end of this booklet. The question numbers must be clearly shown.
• Answer all the questions.
• Where appropriate, your answer should be supported with working. Marks might be
given for using a correct method, even if your answer is wrong.
INFORMATION
• The total mark for this paper is 70.
• The marks for each question are shown in brackets [ ].
• Quality of extended response will be assessed in questions marked with an asterisk (*).
• This document has 16 pages.
ADVICE
• Read each question carefully before you start your answer.
© OCR 2025 [601/5446/9] OCR is an exempt Charity
DC (ST/FC) 344562/5 Turn over
for more: tyrionpapers.com
, 2
1 Catalytic converters on cars use metals such as platinum as heterogeneous catalysts.
Catalytic converters turn exhaust emissions such as carbon monoxide and nitrogen monoxide
into less hazardous products.
(a)
(i) Explain the meaning of the term heterogeneous here.
..........................................................................................................................................................
..................................................................................................................................................... [1]
(ii) Why is carbon monoxide hazardous?
..........................................................................................................................................................
..................................................................................................................................................... [1]
(iii) Write an equation for the reaction of carbon monoxide with nitrogen monoxide to give less
hazardous products.
[1]
(iv) A simple model to explain the function of a heterogeneous catalyst involves four steps.
Complete Step 2 and Step 3 in the sequence below.
Step 1 Reactants are adsorbed onto the surface of the catalyst.
Step 2 ...........................................................................................................................................
Step 3 ...........................................................................................................................................
Step 4 Products are desorbed from the surface of the catalyst.
[1]
© OCR 2025
for more: tyrionpapers.com
, 3
(b)* Explain how a catalyst increases the rate of a reaction.
Draw an energy profile and a Boltzmann distribution.
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..........................................................................................................................................................
..........................................................................................................................................................
..................................................................................................................................................... [6]
Extra answer space if required.
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
© OCR 2025 Turn over
for more: tyrionpapers.com
, 4
2 Ethanol is an important alcohol that is made industrially by the hydration of ethene.
(a) Give the conditions required for this industrial process.
..........................................................................................................................................................
..........................................................................................................................................................
..................................................................................................................................................... [2]
(b) Ethanol can also be made in the laboratory by a two-step process as shown:
CH2=CH2 + H2SO4 CH3CH2OSO3H Step 1
CH3CH2OSO3H + H2O CH3CH2OH + H2SO4 Step 2
Write the overall equation for this two-step process.
[1]
(c) A student does the two-step process in part (b) using an alkene that is a liquid at room
temperature. The reaction is exothermic.
(i) The alkene has a boiling point of 30 °C and is highly flammable.
Suggest a practical arrangement that the student should use to avoid loss of the alkene as a
vapour.
..........................................................................................................................................................
..................................................................................................................................................... [1]
(ii) When the student has carried out both steps, a mixture is left. This mixture contains an alcohol.
The student finds that drops of this mixture turn bromine water from brown to colourless.
Suggest what this colour change tells the student about the conversion of the alkene into alcohol.
..........................................................................................................................................................
..................................................................................................................................................... [1]
© OCR 2025
for more: tyrionpapers.com
Tuesday 20 May 2025 – Morning
AS Level Chemistry B (Salters)
H033/02 Chemistry in depth
Time allowed: 1 hour 30 minutes
You must have:
* 1 8 4 2 2 6 0 9 2 2 *
• the Data Sheet for Chemistry B
You can use:
• a scientific or graphical calculator
• an HB pencil
* H 0 3 3 0 2 *
Please write clearly in black ink. Do not write in the barcodes.
Centre number Candidate number
First name(s)
Last name
INSTRUCTIONS
• Use black ink. You can use an HB pencil, but only for graphs and diagrams.
• Write your answer to each question in the space provided. If you need extra space use
the lined page at the end of this booklet. The question numbers must be clearly shown.
• Answer all the questions.
• Where appropriate, your answer should be supported with working. Marks might be
given for using a correct method, even if your answer is wrong.
INFORMATION
• The total mark for this paper is 70.
• The marks for each question are shown in brackets [ ].
• Quality of extended response will be assessed in questions marked with an asterisk (*).
• This document has 16 pages.
ADVICE
• Read each question carefully before you start your answer.
© OCR 2025 [601/5446/9] OCR is an exempt Charity
DC (ST/FC) 344562/5 Turn over
for more: tyrionpapers.com
, 2
1 Catalytic converters on cars use metals such as platinum as heterogeneous catalysts.
Catalytic converters turn exhaust emissions such as carbon monoxide and nitrogen monoxide
into less hazardous products.
(a)
(i) Explain the meaning of the term heterogeneous here.
..........................................................................................................................................................
..................................................................................................................................................... [1]
(ii) Why is carbon monoxide hazardous?
..........................................................................................................................................................
..................................................................................................................................................... [1]
(iii) Write an equation for the reaction of carbon monoxide with nitrogen monoxide to give less
hazardous products.
[1]
(iv) A simple model to explain the function of a heterogeneous catalyst involves four steps.
Complete Step 2 and Step 3 in the sequence below.
Step 1 Reactants are adsorbed onto the surface of the catalyst.
Step 2 ...........................................................................................................................................
Step 3 ...........................................................................................................................................
Step 4 Products are desorbed from the surface of the catalyst.
[1]
© OCR 2025
for more: tyrionpapers.com
, 3
(b)* Explain how a catalyst increases the rate of a reaction.
Draw an energy profile and a Boltzmann distribution.
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..................................................................................................................................................... [6]
Extra answer space if required.
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
© OCR 2025 Turn over
for more: tyrionpapers.com
, 4
2 Ethanol is an important alcohol that is made industrially by the hydration of ethene.
(a) Give the conditions required for this industrial process.
..........................................................................................................................................................
..........................................................................................................................................................
..................................................................................................................................................... [2]
(b) Ethanol can also be made in the laboratory by a two-step process as shown:
CH2=CH2 + H2SO4 CH3CH2OSO3H Step 1
CH3CH2OSO3H + H2O CH3CH2OH + H2SO4 Step 2
Write the overall equation for this two-step process.
[1]
(c) A student does the two-step process in part (b) using an alkene that is a liquid at room
temperature. The reaction is exothermic.
(i) The alkene has a boiling point of 30 °C and is highly flammable.
Suggest a practical arrangement that the student should use to avoid loss of the alkene as a
vapour.
..........................................................................................................................................................
..................................................................................................................................................... [1]
(ii) When the student has carried out both steps, a mixture is left. This mixture contains an alcohol.
The student finds that drops of this mixture turn bromine water from brown to colourless.
Suggest what this colour change tells the student about the conversion of the alkene into alcohol.
..........................................................................................................................................................
..................................................................................................................................................... [1]
© OCR 2025
for more: tyrionpapers.com
