To calculate average enthalpy of C−H bond in methane following informations are needed (i) dissociation energy of H2 i.e. 21H2(g)⟶H(g);ΔH=x( suppose ) (ii) Sublimation energy of C (graphite) to C(g) C( graphite )⟶C(g);ΔH=y (Suppose) Given C( graphite )+2H2( g)⟶CH4( g);ΔH=75 kJ mol−1
The standard enthalpy of formation (Δ_f H° _298 ) for methane, CH_4 is -74.9 ~kJ ~mol^-1. In order to calculate the average energy given out in the…
JEE Main 2014 — Chemistry Physical Chemistry
2014mcqmedium
The standard enthalpy of formation (ΔfH∘298) for methane, CH4 is −74.9 kJ mol−1. In order to calculate the average energy given out in the formation of a C−H bond from this it is necessary to know which one of the following?
Official previous-year question
Held on 12 Apr 2014 · Verified 6 Jul 2026.
Options
- A
The dissociation energy of the hydrogen molecule, H2.
- B
The first four ionisation energies of carbon.
- C
The dissociation energy of H2 and enthalpy and sublimation of carbon (graphite).
- D
The first four ionisation energies of carbon and electron affinity of hydrogen.
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