Question

The heat of combustion of solid benzoic acid at constant volume is `-321.30 kJ` at `27^(@)C`. The heat of combustion at constant pressure is
A. `-321.30 -300R`
B. `-321.30+300R`
C. `-321.30-150R`
D. `-321.30+900R`

Answer 1

Correct Answer - C
`C_(6)H_(5)COOH(s)+(15)/(2)O_(2)(g)to7CO_(2)(g)+3H_(2)O(l)`
`Deltan+7-(15)/(2)=-(1)/(2)`
`DeltaH=DeltaU+DeltanRT`
`=-321.30-(1)/(2)xxRxx300=-321.30-150R`