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The standard enthalpy of formation of oc...

The standard enthalpy of formation of octane `(C_(8)H_(18))` is `-250kJ //mol`. Calculate the enthalpy of combustion of `C_(8)H_(18)`. The enthalpy of formation of `CO_(2)(g)` and `H_(2)O(l)` are `-394 kJ//mol` and `-286kJ//mol` respectively.

A

`- 5200` kJ/mol

B

`- 5726` kJ/mol

C

`- 5476` kJ/mol

D

`- 5310` kJ/mol

Text Solution

Verified by Experts

The correct Answer is:
C
`C_(8)H_(18)(g)+(25)/(2)O_(2)(g)rarr8CO_(2)(g)+9H_(2)O(l)`
`Delta_(r )H^(@)=8xx(-394)+9xx(-286)-(-250)`
`=-5476 " kJ"//"mol"`
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