of combustion of methane is – X kJ mol –1 . The value of D H 0 is (i) = (ii) (iii)

Question

of combustion of methane is – X kJ mol –1 . The value of D H 0 is (i) = (ii) > (iii) < (iv) = 0

Philoid · Accepted Answer

We know,

ΔH = ΔU + Δn_gRT

Where,

ΔH is change in enthalpy

ΔU is change in Internal energy

Δn_g is difference in number of moles of gaseous substance on both side of equation

The chemical equation for combustion of methane is

CH₄(g) + 2O₂(g) ⇌ CO₂(g) + 2H₂O(l)

In the reactant side, there are 3 mole of gases (1 mole CH₄ and 2 mole O₂)

On product side there is only one mole of gaseous substance (CO₂)

∴ Δn_g = 1 – 3 = - 2

i.e, ΔH = ΔU – 2RT

∴ ΔH > ΔU

Answer is (ii)