Chemical Thermodynamics Chapter 4 Chemistry Class 12 Textbook Solution

    4. Answer the following questions.

    xii. Calculate ΔU at 298 K for the reaction,
    C2H4(g) + HCl(g) →C2H5Cl(g),
    ΔH = -72.3 kJ
    How much PV work is done?
    Ans. : (-69.8 kJ, 2.48 kJ)

    Answer:-

    Given:

    • Enthalpy change = -72.3 kJ
    • Temperature (T) = 298 K

    To find:

    • PV work done
    • Internal energy change (ΔU)

    Formulas:

    1. W = -ΔngRT
    2. ΔH = ΔU + ΔngRT

    Calculations:

    First, calculate the change in the number of moles of gas (Δng): Δng = (moles of product gases) – (moles of reactant gases) Δng = 1 – 2 = -1 mol

    Now, use formula (1) to find the PV work done: W = -ΔngRT W = -(-1 mol) * 8.314 J K^(-1) mol^(-1) * 298 K W = 2477.57 J = 2.48 kJ

    Next, use formula (2) to find the internal energy change (ΔU): ΔU = ΔH – ΔngRT = -72.3 kJ + 2.48 kJ = -69.8 kJ

    Therefore:

    • The PV work done is 2.48 kJ.
    • The internal energy change (ΔU) is -69.8 kJ.
    Q 4.11
    Q 4.12
    Q 4.13

    Chemical Thermodynamics Chapter 4 Chemistry Class 12 Textbook Solution