Pearson Edexcel A-Level Chemistry Advanced Level UNIT 5: Transition Metals and Organic Nitrogen Chemistry January 2024 Authentic Marking Scheme Attached

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Pearson Edexcel International Advanced Level
Friday 12 January 2024
Morning (Time: 1 hour 45 minutes) Paper
reference WCH15/01
Chemistry  


International Advanced Level
UNIT 5: Transition Metals and Organic
Nitrogen Chemistry

You must have: Total Marks
Scientific calculator, Data Booklet, ruler



Instructions
•• Use black ink or ball‑point pen.
If pencil is used for diagrams/sketches/graphs it must be dark (HB or B).
• Fill in the boxes at the top of this page with your name,
centre number and candidate number.
•• Answer all questions.
Answer the questions in the spaces provided
– there may be more space than you need.
Information
•• The total mark for this paper is 90.
The marks for each question are shown in brackets
– use this as a guide as to how much time to spend on each question.
• structure
In the question marked with an asterisk (*), marks will be awarded for your ability to
your answer logically, showing how the points that you make are related or
follow on from each other where appropriate.
• A Periodic Table is printed on the back cover of this paper.
Advice
• Read each question carefully before you start to answer it.
•• Show all your working in calculations and include units where appropriate.
Try to answer every question.
• Check your answers if you have time at the end. Turn over


P73457RA
©2024 Pearson Education Ltd.
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, SECTION A
Answer ALL the questions in this section.




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You should aim to spend no more than 20 minutes on this section.
For each question, select one answer from A to D and put a cross in the box . If you change
your mind, put a line through the box and then mark your new answer with a cross .
1 The apparatus can be used to measure E cell for the reaction shown.

2Cr3+(aq) + Zn(s) → 2Cr2+(aq) + Zn2+(aq)


V
electrode 1 electrode 2


salt bridge




Zn2+(aq) Cr2+(aq) and Cr3+(aq)




(a) Which electrodes are used for this cell?
(1)


electrode 1 electrode 2

A platinum platinum

B platinum chromium

C zinc chromium

D zinc platinum




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, (b) A student wishes to measure the standard cell potential, E cell , of this cell.
The right‑hand cell requires Cr3+ and Cr2+ ions.
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What mass of Cr2(SO4)3 ·18H2O must be dissolved in 1.00 dm3 of deionised water to
give the concentration of Cr3+ ions required to measure this E cell ?
(1)
A 52.0 g

B 196 g

C 358 g

D 716 g


(c) What can be deduced from the fact that, for this reaction, E cell is positive?
(1)
A ΔStotal and ln K are positive

B ΔStotal and ln K are negative

C ΔStotal is positive and ln K is negative
D ΔStotal is negative and ln K is positive

(Total for Question 1 = 3 marks)
Use this space for any rough working. Anything you write in this space will gain no credit.




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, 2 The half‑equations for a hydrogen‑oxygen fuel cell in alkaline solution are shown.

2H2O(l) + 2e– → H2(g) + 2OH–(aq)    E = –0.83 V




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½O2(g) + H2O(l) + 2e– → 2OH–(aq)            E = +0.40 V

(a) The equation for the overall cell reaction is
(1)
A 3H2O(l) + ½O2(g) → H2(g) + 4OH–(aq)

B H2(g) + 4OH–(aq) → 3H2O(l) + ½O2(g)

C H2(g) + ½O2(g) → H2O(l)

D H2O(l) → H2(g) + ½O2(g)


(b) Calculate E cell for the reaction occurring in the hydrogen‑oxygen fuel cell, under
alkaline conditions.
(1)
A –1.23 V
B –0.43 V

C +0.43 V

D +1.23 V

(Total for Question 2 = 2 marks)
Use this space for any rough working. Anything you write in this space will gain no credit.




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