Question
What is the change in entropy of surrounding for the reaction, H _ 2(g) + 1/2\ O _ 2(g) H _2 O _ (l) at 298 K if standard enthalpy of formation of water is -286 kJ ?
MHT CET
Chemistry
Thermodynamics (C)
2026
MHT CET 2026 (16 April Shift 1)
MHT CET Chemistry Question (2026) — Solution
Options
- A. 959.7\ JK ^ -1
- B. 801.5\ JK ^ -1
- C. 850.7\ JK ^ -1
- D. 980.0\ JK ^ -1
Answer
A. 959.7\ JK ^ -1
Step-by-step solution
The standard enthalpy of formation of water is the enthalpy change of the system for the given reaction. H_ sys = -286\ kJ = -286000\ J The heat absorbed by the surroundings at constant pressure is given by: q_ surr = - H_ sys = 286000\ J The change in entropy of the surroundings is calculated as: S_ surr = q_ surr T Substituting the given values: S_ surr = 286000 298 = 959.7\ J K ^ -1 Answer: 959.7\ JK ^ -1
Related: Chemistry — Thermodynamics (C) · All PYQ Banks