Homogeneous and Heterogeneous Equilibria — Predicted 2026

AI-Predicted Question Angles for UPSC 2026

Based on trend analysis, current affairs, and recurring themes in Homogeneous and Heterogeneous Equilibria.

Identification and K-expression for complex heterogeneous systems

high

NEET often tests the ability to apply fundamental rules to slightly more complex scenarios. A question might involve a heterogeneous equilibrium with multiple solid/liquid phases and gaseous components, requiring careful identification of species to include/exclude in the $K_c$ or $K_p$ expression. For example, a reaction like $Fe(s) + 4CO(g) ightleftharpoons Fe(CO)_4(g)$ or $NH_4HS(s) ightleftharpoons NH_3(g) + H_2S(g)$.

Combined $K_p-K_c$ calculation with heterogeneous equilibrium

medium

Students are often comfortable with $K_p-K_c$ relationship for homogeneous gas-phase reactions. A question combining this with a heterogeneous equilibrium would require correct calculation of $Delta n_g$ by only considering gaseous species, which is a common point of error. For instance, providing $K_c$ for $CaCO_3(s) ightleftharpoons CaO(s) + CO_2(g)$ and asking for $K_p$ at a given temperature.

Conceptual question on activity/concentration of pure solids/liquids

medium

Beyond just knowing to exclude them, a question might probe deeper into *why* pure solids/liquids are excluded, or ask about the implications of their constant activity. For example, 'What happens to the concentration of $CaCO_3(s)$ as it decomposes in a closed vessel?' (Answer: it remains constant as long as solid is present, only the *amount* changes).