JEE Main 2024 Chemistry question
The enthalpy of formation of ethane (CH) from ethylene by addition of hydrogen where the bond energies of C–H, C–C, C=C, H–H are 414 kJ, 347 kJ, 615 kJ and 435 kJ respectively is – kJ.
Answer: 125
Solution
ΔH = (615 + 435) − (347 + 2 × 414) = −125 kJ. (The source lists "C–H, C–C, H–H" but gives four values; the third is the C=C energy.)