Enthalpy of Phase Transition — Predicted 2026

AI-Predicted Question Angles for UPSC 2026

Based on trend analysis, current affairs, and recurring themes in Enthalpy of Phase Transition.

Integrated Calorimetry Problems with Phase Change

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NEET loves problems that combine multiple concepts. A predicted angle is a calorimetry problem where a substance undergoing a phase change (e.g., hot steam condensing into cold water) is mixed with another substance, and the final equilibrium temperature is asked. This requires equating heat lost by one component to heat gained by another, incorporating both $mcDelta T$ and $m cdot L$ terms. This tests a deeper understanding of energy conservation and heat transfer during phase changes.

Impact of Intermolecular Forces on Enthalpy Values

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While basic questions on IMFs and $Delta H_{transition}$ are common, a more nuanced question might compare the $Delta H_{vap}$ or $Delta H_{fus}$ values of two different substances and ask for a justification based on their molecular structures and types/strengths of intermolecular forces. For example, comparing water vs. ethanol vs. methane, or explaining why $Delta H_{vap}$ is generally much larger than $Delta H_{fus}$.

Graphical Interpretation of Heating Curves with Quantitative Analysis

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Instead of just asking for calculations, a question might present a heating curve (Temperature vs. Heat Added) and ask students to calculate specific heat capacities from the slopes or latent heats from the lengths of the plateaus. This requires interpreting graphical data and applying formulas in reverse, adding a layer of analytical skill.