Question

The standard enthalpies of formation of CO2,H2O AND CH4 are -393.5,286.2 and -74.8kJ mol-1 respectively. Calculate the enthalpy of combustion of methane.

Answer 1

CH4 + 2O2 → CO2 +2 H2O this is the reaction of combustion of methane.

C + O2 → CO2 ∆H1 = -393 Kj/mol
H2 + 1/2O2→ H2O; ∆ H2 = 286.2 Kj/mol
C + 2H2 → CH4 ; ∆H3 = -74.8 kj/mol

CH4 → C + 2H2 , ∆H3' = 74.8
C + O2 → CO2 ∆ H1 = -393
2( H2 + 1/2O2 → H2O ; ∆H2 = 2× 286.2

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add this reactions,

CH4 + 2O2 → CO2 +2H2O

∆H =( 74.6 -393 +2×286.2 ) Kj/mol
=254 Kj/mol

Answer 2

Answer:

thank you for the answer