DP Chemistry (last assessment 2024)

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Question 20N.2.hl.TZ0.d

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Date November 2020 Marks available [Maximum mark: 2] Reference code 20N.2.hl.TZ0.d
Level hl Paper 2 Time zone TZ0
Command term Calculate Question number d Adapted from N/A
d.
[Maximum mark: 2]
20N.2.hl.TZ0.d

An equation for the combustion of propane is given below.

C3H8(g) + 5O2(g) 3CO2(g) + 4H2O(g)

Calculate ∆S⦵ for the reaction in J K-1, using section 12 of the data booklet.

The standard molar entropy for oxygen gas is 205 J K-1 mol-1.

[2]

Markscheme

4×188.8 «J K−1» AND 3×213.8 «J K−1» AND «1×»270 «J K−1» AND 5×205 «J K−1» ✔

«∆S⦵=4(188.8 J K−1)+3(213.8 J K−1)–[1(270 J K−1)+5(205 J K−1)]=»102«J K−1»  ✔

Award [2] for correct final answer.

Examiners report

Calculating ΔSө, like most other calculations, was well done.

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