Properties of an ideal Raoultian solution: For a solution that strictly obeys Raoult’s law, what are ΔH_mix and ΔV_mix on mixing?

Introduction / Context:When liquid mixtures behave ideally, design calculations simplify dramatically because activities equal mole fractions. Recognizing the thermodynamic hallmarks of ideality helps in VLE modeling and quick feasibility studies.

Given Data / Assumptions:

• Ideal solution behavior (Raoult’s law holds over full composition range).
• Mixing occurs at constant temperature and pressure.

Concept / Approach:Ideality implies no enthalpy or volume effects on mixing. Hence, ΔH_mix = 0 (no heat released/absorbed) and ΔV_mix = 0 (no contraction/expansion). This reflects indistinguishable unlike/like interactions and activity coefficients near unity (γ_i ≈ 1).

Step-by-Step Solution:State the ideal-solution criteria.Map them to thermodynamic statements: ΔH_mix = 0 and ΔV_mix = 0.Choose the option containing both equalities.

Verification / Alternative check:Empirical data for near-ideal pairs (like benzene–toluene) show negligible heat and volume changes upon mixing, validating these criteria.

Why Other Options Are Wrong:Options with nonzero ΔH or ΔV describe nonideal mixtures exhibiting positive/negative deviations from Raoult’s law.

Common Pitfalls:Believing only one of the two (ΔH or ΔV) must be zero; both are required for strict ideality.

Final Answer:both ΔH_mix = 0 and ΔV_mix = 0