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The standard molar heats of formation of...

The standard molar heats of formation of ethane, carbon dioxide, and liquid water are `-21.1, -94.1`, and `-68.3kcal`, respectively. Calculate the standard molar heat of combustion of ethane.

A

`-372` kcal

B

`-240kcal`

C

`162` kcal

D

182.5 kcal

Text Solution

Verified by Experts

The correct Answer is:
A
`C_(2)H_(6)(g)+(7)/(2)O_(2)(g)to2CO_(2)(g)+3H_(2)O(g)`
`DeltaH=2DeltaH_(f(CO_(2)))+3DeltaH_(f(H_(2)O))-DeltaH_(f(C_(2)H_(6)))`
`=2(-94.1)+3(-68.3)-(-21.1)=-372kcal`
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