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Date May 2017 Marks available 1 Reference code 17M.1.sl.TZ2.14
Level SL Paper 1 Time zone TZ2
Command term State Question number 14 Adapted from N/A

Question

Why is the value of the enthalpy change of this reaction calculated from bond enthalpy data less accurate than that calculated from standard enthalpies of formation?

2C2H6(g) + 7O2(g) → 4CO2(g) + 6H2O(g)

A.     All the reactants and products are gases.

B.     Bond enthalpy data are average values for many compounds.

C.     Elements do not have standard enthalpy of formation.

D.     Standard enthalpies of formation are per mole.

Markscheme

B

Examiners report

[N/A]

Syllabus sections

Core » Topic 5: Energetics/thermochemistry » 5.2 Hess’s Law
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