DP Chemistry (last assessment 2024)

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Question 18N.2.sl.TZ0.b.iii

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

3.26 g of iron powder are added to 80.0 cm3 of 0.200 mol dm−3 copper(II) sulfate solution. The following reaction occurs:

Fe (s) + CuSO4 (aq) → FeSO4 (aq) + Cu (s)

The only significant uncertainty is in the temperature measurement.

Determine the absolute uncertainty in the calculated value of ΔH if the uncertainty in the temperature rise was ±0.2 °C.

[2]

Markscheme

ALTERNATIVE 1:

« 0.2 ∘ C × 100 7.5 ∘ C = » 3 %/0.03 ✔

«0.03 × 160 kJ» = «±» 5 «kJ» ✔

 

ALTERNATIVE 2:

« 0.2 ∘ C × 100 7.5 ∘ C = » 3 %/0.03 ✔

«0.03 × 180 kJ» = «±» 5 «kJ» ✔

 

Accept values in the range 4.1–5.5 «kJ».

Award [2] for correct final answer.

 

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