Question

Using average bond enthalpies (linked above), estimate the enthalpy change for the following reaction: CH_(g) + 2O2(g) CO2(g) + 2H2O(g)

Answer 1

Answer:

Given chemical equation is

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

ΔHrxn=Σ n x ΔH^o_f products - Σ m x ΔH^o_f reactants

where n=number of moles of products and m=number of moles of reactants

ΔHrxn= [(1 mol x ΔH^o_f CO2(g)) + (2 mol x ΔH^o_f H2O(g))] - [(1 mol x ΔH^o_f CH4(g)) + (2 mol x ΔH^o_f O2(g))]

ΔH^o_f CH4(g)= -74.85 kJ/mol

ΔH^o_f O2(g)= 0 kJ/mol

ΔH^o_f CO2(g)=-393.51 kJ/mol

ΔH^o_f H2O(g)=-241.82 kJ/mol

ΔHrxn= [(1 mol x -393.51 kJ/mol) + (2 mol x -241.82 kJ/mol)] - [(1 mol x -74.85 kJ/mol) + (2mol x 0 kJ/mol)]

ΔHrxn=-802.3 kJ.