DP Chemistry (last assessment 2024)

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Question 19M.2.hl.TZ2.b

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Date May 2019 Marks available [Maximum mark: 2] Reference code 19M.2.hl.TZ2.b
Level hl Paper 2 Time zone TZ2
Command term Calculate Question number b Adapted from N/A
b.
[Maximum mark: 2]
19M.2.hl.TZ2.b

Phenylethene can be polymerized to form polyphenylethene (polystyrene, PS).

Phenylethene is manufactured from benzene and ethene in a two-stage process. The overall reaction can be represented as follows with ΔGθ = +10.0 kJ mol−1 at 298 K.

Calculate the equilibrium constant for the overall conversion at 298 K, using section 1 of the data booklet.

[2]

Markscheme

ln k «=  − 10000 8.31 × 298 » = –4.04     [✔]

k = 0.0176       [✔]    

 

Note: Award [2] for correct final answer.

Examiners report

Another calculation which most candidates were able to work out, though some failed to convert ΔG given value in kJ mol-1 to J mol-1 or forgot the negative sign. Some used an inappropriate expression of R.

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