DP Chemistry (last assessment 2024)

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Question 19M.3.sl.TZ1.3c

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Date May 2019 Marks available [Maximum mark: 2] Reference code 19M.3.sl.TZ1.3c
Level sl Paper 3 Time zone TZ1
Command term Calculate Question number c Adapted from N/A
c.
[Maximum mark: 2]
19M.3.sl.TZ1.3c

Lithium has many uses.

(c)

Lithium is obtained by electrolysis of molten lithium chloride. Calculate the time, in seconds, taken to deposit 0.694 g Li using a current of 2.00 A.

Q (charge) = I (current) × t (time)

[2]

Markscheme

n«=  m M r = 0.694 6.94 » = 0.100 «mol»  [✔]

«t =  0 .100 mol × 96500  C mo l − 1 2 .00 C  s − 1 =»
4830 «s»  [✔]

 

Note: Accept “4820” OR “4825 «s»”.

Award [2] for correct final answer.

Examiners report

About half the candidates who attempted this were able to calculate the amount of lithium being formed and hence the time required.

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