Question

Can someone please provide an explanation of how to calculate the heat of reaction for the following:

CH4(g) + 2O2(g) -> CO2(g) + 2H2O(g)

Answer is kJ/mol

Thank you!

Answer 1

Ans :-

Given reaction is :

CH₄ (g) + 2O₂ (g) -------------> CO₂ (g) + 2H₂O (g), ΔH⁰_rxn = ?

As,

ΔH⁰_rxn = [Sum of enthalpy of formation of products] - [Sum of enthalpy of formation of reactants]

= [1 x ΔH⁰_f of CO₂ (g) + 2 x ΔH⁰_f of H₂O (g)] - [1 x ΔH⁰_f of CH₄ (g) + 2 x ΔH⁰_f of O₂ (g)]

= [1 x (–393.5 KJ/mol) + 2 x (–241.8 KJ/mol)] - [1 x (–74.6 KJ/mol) + 2 x 0.0 KJ/mol]

= [-393.5 KJ/mol - 483.6 KJ/mol] - [-74.6 KJ/mol]

= - 877.1 KJ/mol + 74.6 KJ/mol

= - 802.5 KJ/mol

Therefore, the heat of the reaction = ΔH0rxn = - 802.5 KJ/mol