Thermodynamics ...

For the reactions A → B; ∆H = + 24 kJ / mol and B → C ; ∆H = -18 kJ / mol, the decreasing order of enthalpy of A, B, C follows the order

The heat of combustion of solid benzoic acid at constant volume is -321.30 kJ at 27° C. The heat of combustion at constant pressure is

If ∆E is the heat of reaction for
C₂ H₅ OH( l ) + 3O₂ (g) →2CO₂(g) + 3H₂O( l )
at constant volume, then ∆H (heat of reaction at constant pressure), at constant temperature is

The heat of formations for CO₂ (g), H₂ O( l ) and CH₄ (g) are - 400 kJ mol^-1 , - 280 kJ mol^-1 and -70 kJ mol^-1 respectively. The heat of combustion of CH₄ in kJ mol^-1 is

The bond dissociation energies of H₂ , Cl₂ and HCl are 104, 58 and 103 kcal mol^-1 respectively. The enthalpy of formation of HCl would be

∆H for the reaction,
C(graphite) + 2H₂ (g) → CH₄ (g) at 298 K and 1 atm is - 17900 cal. The ∆E for the above conversion would be

Assuming that water vapour is an ideal gas, the internal energy change (∆U)when 1 mole of water is vaporised at 1 bar pressure and 100° C, (Given, molar enthalpy of vaporisation of water at 1 bar and 373 K = 41 kJ mol^-1 and R = 8.3 J mol^-1 K^-1 ) will be