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What is theheat of formation of C(6)H(6)...

What is theheat of formation of `C_(6)H_(6)`, given that the heats of combustion of benzene, carbon and hydrogen are 782, 94 and 68K. Cal respectively

A

`+14` kCal

B

`-14` kCal

C

`+28` kCal

D

`-28` kCal

Text Solution

Verified by Experts

The correct Answer is:
A
`C_(6)H_(6) + (15)/(2)O_(2) rarr 6CO_(2) + 3H_(2)O`
`Delta H_("comb") = 6 Delta H_(f_(CO_(2))) + 3 Delta H_(f_(H_(2)O)) - Delta H_(f_(C_(6)H_(6)))`
`-782 = 6 xx (-94) + 3 xx (-68) - Delta H_(f_(C_(6)H_(6)))`
`rArr Delta H_(f_(C_(6)H_(6))) = + 14` Kcal
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