DP Chemistry (last assessment 2024)

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Question 18N.3.sl.TZ0.3b

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Date November 2018 Marks available [Maximum mark: 2] Reference code 18N.3.sl.TZ0.3b
Level sl Paper 3 Time zone TZ0
Command term Calculate Question number b Adapted from N/A
b.
[Maximum mark: 2]
18N.3.sl.TZ0.3b

The presence of very small amounts of lead in calcium-based antacids can be determined using inductively coupled plasma-mass spectroscopy (ICP-MS).

(b)

An unknown antacid sample has a lead ion concentration of 0.50 μg dm‒3.

Calculate the concentration of lead ions in the sample in mol dm‒3.

[2]

Markscheme

[Pb2+] = 0.50 × 10‒6/5.0 × 10–7 «g dm–3» ✔

[Pb2+] « = 0.50 × 10 − 6 g d m − 3 207.20 g mo l − 1 » = 2.4 × 10‒9 «mol dm‒3» ✔

 

Award [2] for correct final answer.

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