Consider the following chemical equations:
2NO₂(g) → 2NO(g) + O₂(g) ∆Hⁿ = +14 kJ mol⁻¹
NO(g) + CO(g) → CO₂(g) + NO(g) ∆Hⁿ = -226 kJ mol⁻¹
2NO₂(g) → N₂O₄(g) ∆Hⁿ = -57 kJ mol⁻¹
N₂(g) + O₂(g) → 2NO(g) ∆Hⁿ = +181 kJ mol⁻¹
Which one of the following graphs is consistent with the chemical equations above? - VCE - SSCE Chemistry - Question 18 - 2021 - Paper 1
Question 18
Consider the following chemical equations:
2NO₂(g) → 2NO(g) + O₂(g) ∆Hⁿ = +14 kJ mol⁻¹
NO(g) + CO(g) → CO₂(g) + NO(g) ∆Hⁿ = -226 kJ mol⁻¹
2NO₂(g) → N₂O₄(g) ∆Hⁿ =... show full transcript
Worked Solution & Example Answer:Consider the following chemical equations:
2NO₂(g) → 2NO(g) + O₂(g) ∆Hⁿ = +14 kJ mol⁻¹
NO(g) + CO(g) → CO₂(g) + NO(g) ∆Hⁿ = -226 kJ mol⁻¹
2NO₂(g) → N₂O₄(g) ∆Hⁿ = -57 kJ mol⁻¹
N₂(g) + O₂(g) → 2NO(g) ∆Hⁿ = +181 kJ mol⁻¹
Which one of the following graphs is consistent with the chemical equations above? - VCE - SSCE Chemistry - Question 18 - 2021 - Paper 1
Step 1
Enthalpy Change of 2NO₂(g) → 2NO(g) + O₂(g)
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Answer
This reaction has a positive enthalpy change (+14 kJ mol⁻¹), indicating that it is endothermic. The graph should show an increase in enthalpy as the reaction progresses.
Step 2
Enthalpy Change of NO(g) + CO(g) → CO₂(g) + NO(g)
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Answer
This reaction has a significant negative enthalpy change (-226 kJ mol⁻¹), indicating it is exothermic and the graph will show a drop in enthalpy.
Step 3
Enthalpy Change of 2NO₂(g) → N₂O₄(g)
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Answer
With a negative enthalpy change (-57 kJ mol⁻¹), this reaction is also exothermic, showing a decrease in enthalpy.
Step 4
Enthalpy Change of N₂(g) + O₂(g) → 2NO(g)
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Answer
This reaction has a positive enthalpy change (+181 kJ mol⁻¹), indicating it is endothermic and will appear as an increase in enthalpy.
Step 5
Choosing the Correct Graph
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Answer
After analyzing the enthalpy changes, the most consistent graph with the chemical equations is option C, as it represents both endothermic and exothermic reactions accurately.
