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The standard heats of combustion of CH(4...

The standard heats of combustion of `CH_(4)(g) and C_(2)H_(6)(g)` are -890`kJ*mol^(-1)` and -1560 `kJ*mol^(-1)`, respectively. Why is the calorific value of `C_(2)H_(6)(g)` lower than that of `CH_(4)(g)`?

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The calorific value of `C_(2)H_(6)(g)`
`=("heat of combustion of "C_(2)H_(6)(g))/("Molar mass of "C_(2)H_(6))=(1560kJ*mol^(-1))/(30g*mol^(-1))`
`=52kJ*g^(-1)`.
The calorific value of `CH_(4)(g)=(890kJ*mol^(-1))/(16g*mol^(-1))`
`=55.62kJ*g^(-1)`.
Therefore, the calorific value of `CH_(4)(g)` is greater than that of `C_(2)H_(6)(g)` although `C_(2)H_(6)(g)` has a higher value of heat of combustion that `CH_(4)(g)`.
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