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Date November 2017 Marks available 3 Reference code 17N.2.sl.TZ0.4
Level SL Paper 2 Time zone TZ0
Command term Determine Question number 4 Adapted from N/A

Question

Menthol is an organic compound containing carbon, hydrogen and oxygen.

Complete combustion of 0.1595 g of menthol produces 0.4490 g of carbon dioxide and 0.1840 g of water. Determine the empirical formula of the compound showing your working.

[3]
a.

0.150 g sample of menthol, when vaporized, had a volume of 0.0337 dm3 at 150 °C and 100.2 kPa. Calculate its molar mass showing your working.

[2]
b.

Markscheme

carbon: «\(\frac{{0.4490\,{\text{g}}}}{{44.01\,{\text{g}}\,{\text{mo}}{{\text{l}}^{ - 1}}}}\)» = 0.01020 «mol» / 0.1225 «g»

OR

hydrogen: «\(\frac{{0.1840 \times 2}}{{18.02}}\)» = 0.02042 «mol» / 0.0206 «g»

oxygen: «0.1595 – (0.1225 + 0.0206)» = 0.0164 «g» / 0.001025 «mol»

empirical formula: C10H20O

Award [3] for correct final answer.

a.

temperature = 423 K

OR

«M \( = \frac{{mRT}}{{pV}}\)

«\( = \frac{{0.150\,{\text{g}} \times 8.31\,{\text{J}} {{\text{ K}}^{ - 1}}\,{\text{mol}}{}^{ - 1} \times 423\,{\text{K}}}}{{100.2\,{\text{kPa}} \times 0.0337\,{\text{d}}{{\text{m}}^3}}} = \)» 156 «g mol–1»

Award [1] for correct answer with no working shown.

Accept “pV = nRT AND n = \(\frac{m}{M}\)” for M1.

b.

Examiners report

[N/A]
a.
[N/A]
b.

Syllabus sections

Core » Topic 1: Stoichiometric relationships » 1.2 The mole concept
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