DP Chemistry (last assessment 2024)

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Question 22M.2.sl.TZ1.b(ii)

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Date May 2022 Marks available [Maximum mark: 2] Reference code 22M.2.sl.TZ1.b(ii)
Level sl Paper 2 Time zone TZ1
Command term Determine Question number b(ii) Adapted from N/A
b(ii).
[Maximum mark: 2]
22M.2.sl.TZ1.b(ii)

When heated in air, magnesium ribbon reacts with oxygen to form magnesium oxide.

The reaction in (a)(i) was carried out in a crucible with a lid and the following data was recorded:

Mass of crucible and lid = 47.372 ±0.001 g

Mass of crucible, lid and magnesium ribbon before heating = 53.726 ±0.001 g

Mass of crucible, lid and product after heating = 56.941 ±0.001 g

 

Determine the percentage uncertainty of the mass of product after heating.

[2]

Markscheme

mass of product «=56.941 g-47.372 g»=9.569 «g» ✔

⟨⟨100 × 2×0.001 g9.569 g=0.0209⟩⟩ = 0.02 «%» ✔

 

Award [2] for correct final answer

Accept 0.021%

Examiners report

Only a handful could work out the correct answer. Most had no real idea and quite a lot of blank responses. There also seems to be significant confusion between "percent uncertainty" and "percent error".

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