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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 `CO_(2)(g)` and `H_(2)O(l)` are `-394 kJ//mol` and `-286kJ//mol` respectively.

A

`-5200kJ//mol`

B

`-5726kJ//mol`

C

`-5476kJ//mol`

D

`-5310kJ//mol`

Text Solution

Verified by Experts

The correct Answer is:
3
`C_(5)H_(18)(g)+(25)/(2)O_(2)(g)rarr8CO_(2)(g)+9H_(2)O(l)`
`Delta_(r)H^(@)=8xx(-394)+9xx(-286)-(-250)`
`=5476kJ//mol`.
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Knowledge Check

  • The standard enthalpy of formation of octane (C_(8)H_(18)) is -250 KJ/mol. Calculate the enthalpy of formation of CO_(2)(g) and H_(2)O_(l) are -394 KJ/mol and -286 KJ/ mol respectively :

    A
    -5200 KJ/mol
    B
    -5726 KJ/mol
    C
    -5476 KJ/mol
    D
    -5310 KJ/mol
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