DP Chemistry (first assessment 2025)

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Question 23M.2.SL.TZ1.4

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Date May 2023 Marks available [Maximum mark: 4] Reference code 23M.2.SL.TZ1.4
Level SL Paper 2 Time zone TZ1
Command term Formulate, Outline, State Question number 4 Adapted from N/A
4.
[Maximum mark: 4]
23M.2.SL.TZ1.4

Redox reactions can be used to produce electricity.

(a)

State the oxidation state of sulfur in copper (II) sulfate.

[1]

Markscheme

+6/VI ✓

 

Do not accept 6/6+.

(b)

A voltaic cell was constructed using a copper (II) sulfate/copper half-cell and a zinc sulfate/zinc half-cell.

(b.i)

Outline why electrons flow from zinc to copper when these half cells are connected with a wire. Use section 25 of the data booklet.

[1]

Markscheme

Zinc more reactive/ «better» reducing agent/ «more» easily oxidized/loses electrons «more» easily. ✓
 

Accept “zinc higher in the activity «series»”.
Accept “zinc has a negative electrode potential/Cu has a positive electrode potential”.

(b.ii)

Formulate equations for the reactions taking place at each electrode.

 

Anode (negative electrode):  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

Cathode (positive electrode): . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

[2]

Markscheme

Anode (negative electrode):
Zn(s) → Zn2+(aq) + 2e−  ✓

Cathode (positive electrode):
Cu2+(aq) + 2e− → Cu(s) ✓

 

Award [1 max] for equilibria.
Award [1 max] for equations at the wrong electrodes.
State symbols not required for mark.