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Convert between delta H and delta U using delta H = delta U + delta n RT

This type of question, asked 4 times: 16 May 2023 S2, 14 May 2024 S1, 15 Apr 2026 S1, 18 Apr 2026 S1. All 4 questions below, oldest first.

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  1. Question 1

    16 May 2023 S2

    62
    Calculate standard internal energy change for OF2(g)+H2O(g)→2HF(g)+O2(g)\text{OF}_2(g) + \text{H}_2\text{O}(g) \rightarrow 2\text{HF}(g) + \text{O}_2(g) at 300 K, if ΔfH∘\Delta_f H^\circ of OF2(g)\text{OF}_2(g), H2O(g)\text{H}_2\text{O}(g) and HF(g)\text{HF}(g) are 20,−25020, -250 and −270-270 kJ mol−1^{-1} respectively. R=8.314R = 8.314 J K−1^{-1} mol−1^{-1}

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  2. Question 2

    14 May 2024 S1

    88
    Calculate ΔH\Delta H for the following reaction at 25∘C25^\circ\text{C}. NH2CN(g)+32O2(g)→N2(g)+CO2(g)+H2O(l)\text{NH}_2\text{CN}_{(g)}+\dfrac{3}{2}\text{O}_{2(g)}\rightarrow\text{N}_{2(g)}+\text{CO}_{2(g)}+\text{H}_2\text{O}_{(l)} (ΔU=−740.5 kJ\Delta U=-740.5\,\text{kJ}, R=8.314 J K−1mol−1R=8.314\,\text{J K}^{-1}\text{mol}^{-1})

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  3. Question 3

    15 Apr 2026 S1

    7
    C2H5OH(l)+3O2(g)→2CO2(g)+3H2O(l)\mathrm{C_2H_5OH}(l) + 3\mathrm{O_2}(g) \rightarrow 2\mathrm{CO_2}(g) + 3\mathrm{H_2O}(l) The value of enthalpy change (ΔH)(\Delta H) for above reaction at 27 ∘C27\ ^\circ\mathrm{C} is −1366.5 kJ mol−1-1366.5\ \mathrm{kJ\,mol^{-1}}. Then value of internal energy change for the same reaction at this temperature will be

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  4. Question 4

    18 Apr 2026 S1

    7
    Calculate ΔH\Delta\mathrm{H} for the following reaction at 300 K 2C(s)+3H2(g)⟶C2H6(g)\mathrm{2C_{(s)} + 3H_{2(g)} \longrightarrow C_2H_{6(g)}} if ΔU\Delta\mathrm{U} for the reaction is −80-80 kJ (R=8.314 JK−1mol−1\mathrm{R} = 8.314\ \mathrm{JK^{-1}mol^{-1}})

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