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Question 18N.2.hl.TZ0.1b.i

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Date November 2018 Marks available [Maximum mark: 2] Reference code 18N.2.hl.TZ0.1b.i
Level hl Paper 2 Time zone TZ0
Command term Calculate Question number b.i Adapted from N/A
b.i.
[Maximum mark: 2]
18N.2.hl.TZ0.1b.i

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)

(b.i)

The reaction was carried out in a calorimeter. The maximum temperature rise of the solution was 7.5 °C.

Calculate the enthalpy change, ΔH, of the reaction, in kJ, assuming that all the heat released was absorbed by the solution. Use sections 1 and 2 of the data booklet.

[2]

Markscheme

ALTERNATIVE 1:

q = «80.0 g × 4.18 J g–1 K–1 × 7.5 K =» 2.5 × 103 «J»/2.5 «kJ» ✔

«per mol of CuSO4 =  − 2.5 kJ 0.0160 mol = − 1.6 × 10 2  kJ mol–1»

«for the reaction» ΔH = –1.6 × 102 «kJ» ✔

 

ALTERNATIVE 2:

q = «80.0 g × 4.18 J g–1 K–1 × 7.5 K =» 2.5 × 103 «J»/2.5 «kJ» ✔

«nCu = 0.872 63.55 = 0.0137 mol»

«per mol of CuSO4 =  − 2.5 kJ 0.0137 mol = − 1.8 × 10 2 kJ mol–1»

«for the reaction» ΔH = –1.8 × 102 «kJ» ✔

 

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