JEE Main · 2025 · Shift-IImediumTHERMO-146

Consider the given data: (A) HCl(g) + 10H2O(l) - HCl.10H2O, H = -69.01 kJ mol-1 (B) HCl(g) + 40H2O(l) - HCl.40H2O, H =…

Thermodynamics · Class 11 · JEE Main Previous Year Question

Question

Consider the given data:

(A) \ceHCl(g)+10H2O(l)−>HCl.10H2O\ce{HCl(g) + 10H2O(l) -> HCl.10H2O}, ΔH=−69.01\Delta H = -69.01 kJ mol−1^{-1}

(B) \ceHCl(g)+40H2O(l)−>HCl.40H2O\ce{HCl(g) + 40H2O(l) -> HCl.40H2O}, ΔH=−72.79\Delta H = -72.79 kJ mol−1^{-1}

Choose the correct statement:

Options
  1. a

    Dissolution of gas in water is an endothermic process

  2. b

    The heat of solution depends on the amount of solvent.

    ✓
  3. c

    The heat of dilution for the HCl (\ceHCl.10H2O\ce{HCl.10H2O} to \ceHCl.40H2O\ce{HCl.40H2O}) is 3.783.78 kJ mol−1^{-1}.

  4. d

    The heat of formation of HCl solution is represented by both (A) and (B)

Correct Answerb

The heat of solution depends on the amount of solvent.

Detailed Solution

🧠 Heat of solution depends on the amount of solvent — a dissolved substance in dilute vs. concentrated solution releases different heat The two experiments show HCl dissolving in 10 mol vs. 40 mol of water, releasing 69.01 vs. 72.79 kJ. The difference (3.78 kJ) is heat of dilution — not heat of solution.

Evaluating options:

  • (a) False — dissolution of HCl is exothermic (both values are negative).
  • (b) True — the heat released per mole of solute changes with the amount of solvent.
  • (c) False — the heat of dilution is 72.79−69.01=3.78 kJ72.79 - 69.01 = 3.78\,\text{kJ}, but this is the heat evolved on further dilution, not the heat of the solution process itself.
  • (d) False — the standard enthalpy of formation of HCl solution is not represented by either; these are heats of solution.

Answer: (b)\boxed{\text{Answer: (b)}}

Practice this question with progress tracking

Want timed practice with adaptive difficulty? Solve this question (and hundreds more from Thermodynamics) inside The Crucible, our adaptive practice platform.

Practice in The Crucible →Browse Thermodynamics chapter →

More JEE Main Thermodynamics PYQs

2025hard

Arrange the following in order of magnitude of work done by the system / on the system at constant temperature: (a) |Wreversible| for expansion in infinite stage. (b) |Wirreversible| for expansion in…

2025medium

If C(diamond) - C(graphite) + X kJ mol-1 C(diamond) + O2(g) - CO2(g) + Y kJ mol-1 C(graphite) + O2(g) - CO2(g) + Z kJ mol-1 At constant temperature. Then:

2019medium

The difference between H and U is ( H - U), when the combustion of one mole of heptane (l) is carried out at a temperature T, is equal to:

2025medium

Two vessels A and B are connected via stopcock. Vessel A is filled with a gas at a certain pressure. The entire assembly is immersed in water and allowed to come to thermal equilibrium. After opening…

2025hard

Which of the following graphs correctly represents the variation of thermodynamic properties of Haber's process? (N2(g) + 3H2(g) <= 2NH3(g))

View all 58 Thermodynamics PYQs →
Consider the given data: (A) HCl(g) + 10H2O(l) - HCl.10H2O, H = -69.01 kJ mol-1 (B) HCl(g) +… (JEE Main 2025) | Canvas Classes