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Date November 2009 Marks available 1 Reference code 09N.1.sl.TZ0.17
Level SL Paper 1 Time zone TZ0
Command term Deduce Question number 17 Adapted from N/A

Question

Use the average bond enthalpies below to calculate the enthalpy change, in kJ, for the following reaction.

\[{{\text{H}}_2}{\text{(g)}} + {{\text{I}}_2}{\text{(g)}} \to {\text{2HI(g)}}\]

N09/4/CHEMI/SPM/ENG/TZ0/17

A.     +290

B.     +10

C.     –10

D.     –290

Markscheme

C

Examiners report

One G2 comment stated that the question should have asked for the enthalpy change in the reaction in units of \({\text{kJ}}\,{\text{mo}}{{\text{l}}^{ - 1}}\) instead of kJ. This aspect of units has been discussed in detail in several previous subject reports and teachers are referred to these reports for further reference.

Syllabus sections

Core » Topic 5: Energetics/thermochemistry » 5.3 Bond enthalpies
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