Question
In a particular reaction, 4 kJ heat is released by the system and 12 kJ work done on the system. Calculate the H and U.
MHT CET
Chemistry
Thermodynamics (C)
2026
MHT CET 2026 (16 April Shift 1)
MHT CET Chemistry Question (2026) — Solution
Options
- A. H = 4 kJ and U = 16 kJ
- B. H = -4 kJ and U = 8 kJ
- C. H = -4 kJ and U = -16 kJ
- D. H = 4 kJ and U = -16 kJ
Answer
B. H = -4 kJ and U = 8 kJ
Step-by-step solution
Heat released by the system, q = -4 kJ. Work done on the system, w = +12 kJ. According to the first law of thermodynamics: U = q + w U = -4 + 12 = 8 kJ. For a reaction at constant pressure, the enthalpy change is equal to the heat exchanged: H = q_p = -4 kJ. Answer: H = -4 kJ and U = 8 kJ
Related: Chemistry — Thermodynamics (C) · All PYQ Banks