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Oxford Cambridge and RSA
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AS-Level OCR 2025 Chemistry B (Salters) Paper 2
FGCCHCGFGHSJSCSCCXUXHKJH Y66787678UH I8767876TGV I87VCBNKCJZ XXJGX X98XYXX
Tuesday 20 May 2025 – Morning
AS Level Chemistry B (Salters)
H033/02 Chemistry in depth
Time allowed: 1 hour 30 minutes
CX
Turn over
1
, 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
, 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.
..........................................................................................................................................................
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© OCR 2025 Turn over
CKCIUDCHDCJCDCDJCDKCLDCPDOCKDCCDCDCCKJCNMC CDCHDU876DTGEH9E87YGB I9
Oxford Cambridge and RSA
DFDFF DJDUYD8E73YGV 3E9387YD DOC0987YC CODC9D87YV XLXM K9872E 9D7GVD NC97GDV COC0CCV C
YVBCBXJCC USYTSGDS7D6TEG EI3876ETWD DJS678IJEN DSD7W6DTGD SSGSYS9DSIDUSV DSKIS876F
AS-Level OCR 2025 Chemistry B (Salters) Paper 2
FGCCHCGFGHSJSCSCCXUXHKJH Y66787678UH I8767876TGV I87VCBNKCJZ XXJGX X98XYXX
Tuesday 20 May 2025 – Morning
AS Level Chemistry B (Salters)
H033/02 Chemistry in depth
Time allowed: 1 hour 30 minutes
CX
Turn over
1
, 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
, 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.
..........................................................................................................................................................
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..........................................................................................................................................................
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..........................................................................................................................................................
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© OCR 2025 Turn over
