Igcse Model Questions Vol1 2025 Chemistry Question 14
Practice objective / multiple choice question 14 from the 2025 Igcse Model Questions Vol1 Chemistry examination.
Average bond enthalpies (kJ mol(^{-1})) are: C=C = 614, C-C = 348, C-H = 413, H-H = 436. Using these values, calculate the enthalpy change for the hydrogenation reaction \(\mathrm{C_2H_4(g) + H_2(g) \rightarrow C_2H_6(g)}\). The standard enthalpies of formation are: \(\Delta H_f^\circ(\mathrm{C_2H_4}) = +52\) kJ mol(^{-1}), \(\Delta H_f^\circ(\mathrm{C_2H_6}) = -84\) kJ mol(^{-1}), \(\Delta H_f^\circ(\mathrm{H_2}) = 0\). Using the formation data, calculate the enthalpy change for the same reaction. State both values and indicate which method predicts a more exothermic reaction, giving a brief explanation for any difference.
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This is Igcse Model Questions Vol1 2025 Chemistry Question 14. It is one of the objective questions from the 2025 Igcse Model Questions Vol1 Chemistry examination.
Difficulty level: Hard .
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