Question

The combustion of benzene (1) gives `CO_(2)(g)` and `H_(2)O(1)`. Given that heat of combustion of benzene at constant volume is `.^(-)3263.9 kJ mol^(-1) " at "25^(@)C`, heat of combustion (in kJ `mol^(-1)`) of benzene at constant pressure will be
`(R=8.314 JK^(-1) mol^(-1))`
A. `- 452.46`
B. 3260
C. `- 3267.6`
D. 4152.6

Answer 1

Correct Answer - C
`C_(6)H_(6("liq"))+7.5O_(2(g))rarr6CO_(2(g))+3H_(2)O_("liq")`
`Deltan_((g))=6-7.5=-15`
`DeltaH=DeltaE+Deltan_((g))RT`
`DeltaH=-3263.9kJ-(1.5xx8.314xx298)/(1000)kJ=-3267.6 kJ`