A-LevelChemistryChemical energeticsOct/Nov 2011Paper 1 Q171 Mark
The standard enthalpy changes of formation of HCl and HI are –92 kJ mol⁻¹ and +26 kJ mol⁻¹ respectively. Which statement is most important in explaining this difference?
AChlorine is more electronegative than iodine.
BThe activation energy for the H2 + Cl2 reaction is much less than that for the H2 + I2 reaction.
CThe bond energy of HI is smaller than the bond energy of HCl.
DThe bond energy of I2 is smaller than the bond energy of Cl2.
✓ Correct Answer
The correct answer is C. This question tests the candidate's understanding of chemical energetics within the Chemistrysyllabus. The examiner's mark scheme requires...
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