Gce Model Questions Vol1 2021 Chemistry Question 43

Practice objective / multiple choice question 43 from the 2021 Gce Model Questions Vol1 Chemistry examination.

Gce Model Questions Vol1 2021 Chemistry Objective / Multiple Choice Hard Difficulty
Question 43 GCE_MODEL_QUESTIONS_VOL1 • 2021 • CHEMISTRY • objective

A hydrocarbon of unknown formula is combusted completely in excess oxygen. The combustion yields \(44.8\ \text{g}\) of \(\mathrm{CO_2}\) and \(18.0\ \text{g}\) of \(\mathrm{H_2O}\). The molar mass of the hydrocarbon is \(70\ \text{g mol^{-1}}\). (i) Determine its molecular formula. (ii) Assuming the hydrocarbon is a straight‑chain alkene containing one C=C double bond, estimate the standard enthalpy change for its combustion per mole using the average bond enthalpies: C-C 348 kJ mol\(^{-1}\), C=C 614 kJ mol\(^{-1}\), C-H 413 kJ mol\(^{-1}\), C=O 799 kJ mol\(^{-1}\), O-H 463 kJ mol\(^{-1}\).

Answer Options

A. Molecular formula \(C_5H_{12}\); \(\Delta H_{comb}\approx -2.9\times10^{3}\ \text{kJ mol}^{-1}\)
B. Molecular formula \(C_6H_{12}\); \(\Delta H_{comb}\approx -3.6\times10^{3}\ \text{kJ mol}^{-1}\)
C. Molecular formula \(C_4H_{8}\); \(\Delta H_{comb}\approx -2.5\times10^{3}\ \text{kJ mol}^{-1}\)
Correct Answer D. Molecular formula \(C_5H_{10}\); \(\Delta H_{comb}\approx -3.1\times10^{3}\ \text{kJ mol}^{-1}\)
Correct Answer
D
Correct Option:
Molecular formula \(C_5H_{10}\); \(\Delta H_{comb}\approx -3.1\times10^{3}\ \text{kJ mol}^{-1}\)

About This Question

This is Gce Model Questions Vol1 2021 Chemistry Question 43. It is one of the objective questions from the 2021 Gce Model Questions Vol1 Chemistry examination.

Difficulty level: Hard .

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