A-LevelChemistryChemical energeticsMay/June 2023Paper 1 Q101 Mark
Nitrogen monoxide is rapidly oxidised to nitrogen dioxide. 2NO(g) + O₂(g) → 2NO₂(g) Nitrogen dioxide can then dimerise to form dinitrogen tetroxide. 2NO₂(g) → N₂O₄(g) ΔH° = –58 kJ mol⁻¹ ΔHᶠNO = +91 kJ mol⁻¹ and ΔHᶠNO₂ = +34 kJ mol⁻¹ What is the value of the standard enthalpy change for the reaction shown? 2NO(g) + O₂(g) → N₂O₄(g)
A+56 kJ mol⁻¹
B–1 kJ mol⁻¹
C–115 kJ mol⁻¹
D–172 kJ mol⁻¹
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The correct answer is D. This question tests the candidate's understanding of chemical energetics within the Chemistrysyllabus. The examiner's mark scheme requires...
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