AIIMS2019Chemistry-Thermodynamics

AIIMS 2019 Chemistry Enthalpy Change MCQ Question

Type: MCQ-numerical-Medium-Class 11

One mole of a non-ideal gas undergoes a change of state (2.0 atm, 3.0 L, 95 K)(4.0 atm, 5.0 L, 245 K)(2.0\text{ atm},\ 3.0\text{ L},\ 95\text{ K}) \rightarrow (4.0\text{ atm},\ 5.0\text{ L},\ 245\text{ K}) with a change in internal energy, ΔU=30.0 L atm\Delta\text{U} = 30.0\text{ L atm}. The change in enthalpy ΔH\Delta\text{H} of the process in L atm\text{L atm} is.

A

40.0

B

42.3

C

44.0

D

Not defined because pressure is not constant

Correct Answer

Option C

Detailed Explanation

Option C is correct because it accurately represents the change in enthalpy (ΔH) as the difference between the internal energy (U) and the work done by the system, expressed as ΔH = (U₂ - U₁) + (P₂V₂ - P₁V₁). This formulation aligns with the first law of thermodynamics, where enthalpy is defined as H = U + PV.

Option A is incorrect as it does not account for the pressure-volume work associated with the system. Option B, while it includes the correct terms, does not simplify to the proper expression for ΔH. Option D presents a numerical calculation that lacks context and does not relate to the enthalpy change formula.

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