The standard enthalpy of formation (Δ H°f) at 298 K for methane, CH4(g), is - 74.8 kJ mol-1. The additional information required to determine the average energy for C—H bond formation would be:

Question

The standard enthalpy of formation (Δ H°f) at 298 K for methane, CH4(g), is - 74.8 kJ mol-1. The additional information required to determine the average energy for C—H bond formation would be: (A) the dissociation energy of H2 and enthalpy of sublimation of carbon (B) latent heat of vaporization of methane (C) the first four ionization energies of carbon and electron gain enthalpy of hydrogen (D) the dissociation energy of hydrogen molecule, H2.

Tardigrade Admin · Accepted Answer

Carbon is found in solid state. The state ol substance affects the enthalpy change. C (s) → C (g) Sublimation and H2(g) → 2H(g) dissociation are required for C—H bond

Q. The standard enthalpy of formation $(Δ H_{f}^{\circ})$ at 298 K for methane, $C H_{4} (g)$ , is $- 74.8 k J m o l^{- 1}$ . The additional information required to determine the average energy for C—H bond formation would be:

the dissociation energy of $H_{2}$ and enthalpy of sublimation of carbon

latent heat of vaporization of methane

the first four ionization energies of carbon and electron gain enthalpy of hydrogen

the dissociation energy of hydrogen molecule, $H_{2}$ .

Carbon is found in solid state. The state ol substance affects the enthalpy change.
$C (s) \to C (g)$ Sublimation
and $H_{2} (g) \to 2 H (g)$ dissociation
are required for C—H bond

Q. The standard enthalpy of formation (ΔHf∘​) at 298 K for methane, CH4​(g), is −74.8kJmol−1. The additional information required to determine the average energy for C—H bond formation would be:

the dissociation energy of H2​ and enthalpy of sublimation of carbon