Question
At 25\ ^ C standard enthalpy of combustion of H _2, Cyclohexene and cyclohexane are -241, -3800 and -3920 kJ mol ^ -1 respectively. What is the heat of hydrogenation of cyclohexene?
MHT CET
Chemistry
Thermodynamics (C)
2026
MHT CET 2026 (17 April Shift 1)
MHT CET Chemistry Question (2026) — Solution
Options
- A. -121 kJ
- B. -242 kJ
- C. 121 kJ
- D. 363 kJ
Answer
A. -121 kJ
Step-by-step solution
The hydrogenation reaction of cyclohexene is given by: C _6 H _ 10 + H _2 C _6 H _ 12 The enthalpy of hydrogenation can be calculated using the standard enthalpies of combustion of the reactants and products: H = H_c( Reactants ) - H_c( Products ) H = H_c( C _6 H _ 10 ) + H_c( H _2) - H_c( C _6 H _ 12 ) Substituting the given values: H = -3800 + (-241) - (-3920) H = -4041 + 3920 = -121 kJ mol ^ -1 Answer: -121 kJ
Related: Chemistry — Thermodynamics (C) · All PYQ Banks