A-LevelChemistryChemical energeticsOct/Nov 2023Paper 1 Q111 Mark
Nitric acid is made industrially by the oxidation of ammonia. The overall equation for the process is shown. equation 1 NH3 + 2O2 → HNO3 + H2O The process happens in three stages. The equations and enthalpy changes for these stages are given. stage 1 4NH3 + 5O2 → 4NO + 6H2O ΔH = –904 kJ mol⁻¹ stage 2 2NO + O2 → 2NO2 ΔH = –114 kJ mol⁻¹ stage 3 4NO2 + O2 + 2H2O → 4HNO3 ΔH = −348 kJ mol⁻¹ What is the enthalpy change of the process shown in equation 1?
A-1480 kJ mol⁻¹
B-370 kJ mol⁻¹
C-341.5 kJ mol⁻¹
D+82 kJ mol⁻¹
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The correct answer is B. This question tests the candidate's understanding of chemical energetics within the Chemistrysyllabus. The examiner's mark scheme requires...
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