O-LevelChemistryRates of Reaction5070/12 · May/June 2014 · Q151 Mark

Nitrogen monoxide is an atmospheric pollutant that is formed in car engines by the reaction between nitrogen and oxygen. N₂(g) + O₂(g) → 2NO(g) ΔΗ = +66 kJ/mol Which diagram represents the energy profile for this reaction?

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AEnergy profile diagram showing an endothermic reaction (products at higher enthalpy than reactants) with activation energy.

BEnergy profile diagram showing an exothermic reaction (products at lower enthalpy than reactants) with activation energy.

CEnergy profile diagram showing an exothermic reaction (products at lower enthalpy than reactants) with activation energy.

DEnergy profile diagram showing an endothermic reaction (products at higher enthalpy than reactants) with activation energy.

✓ Correct answer

A: Energy profile diagram showing an endothermic reaction (products at higher enthalpy than reactants) with activation energy.

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Topic: Rates of Reaction, O-Level Chemistry (syllabus 5070). Multiple choice, 1 mark.
Source: O-Level Chemistry, May/June 2014 Paper 1 Variant 2, question 15.

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