DP Chemistry (last assessment 2024)

Question 20N.3.sl.TZ0.4b(iii)

Date	November 2020	Marks available	[Maximum mark: 3]	Reference code	20N.3.sl.TZ0.4b(iii)
Level	sl	Paper	3	Time zone	TZ0
Command term	Calculate	Question number	b(iii)	Adapted from	N/A

b(iii).

[Maximum mark: 3]

20N.3.sl.TZ0.4b(iii)

There has been significant growth in the use of carbon nanotubes, CNT.

(b(iii))

Calculate the theoretical mass of magnesium obtained if a current of $3.00 A$ is used for $10.0$ hours. Use charge $(Q) = c u r r e n t (I) \times t i m e (t)$ and section 2 of the data booklet

[3]

Markscheme

$« Q = I \times t = 3.00 \times 10.0 \times 3600 = » 108 000 C$ ✔

$« \frac{Q}{F} = \frac{108 000 C}{96 500 C {mol}^{- 1}} = » 1.12 « mol e^{-} »$ ✔

$« \frac{1.12 mol}{2} = 0.560 mol Mg »$
$« m = 0.560 mol \times 24.31 g {mol}^{- 1} = » 13.6 « g »$ ✔

Award [3] for correct final answer.

Examiners report

This was a very popular option with approximately 34% of candidates attempting Option B. Many students appeared well prepared for this option. Some candidates continue to provide answers with a heavy Biology bias that often make them lose valuable points.

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Options » A: Materials » A.2 Metals and inductively coupled plasma (ICP) spectroscopy

Options » A: Materials

Question 20N.3.sl.TZ0.4b(iii)

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