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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)+(25)/(2)O_(2)(g)rarr8CO_(2)+9H_(2)O(l)`
`DeltaH_(t)=E(DeltaH_(f)^(@))_("Product")-E(DeltaH_(f)^(@))_("reactant")`
`=[8(-394)+9(-286)]-[-250+0]`
`=[-3152-2574]+250`
`=-5726+250`
`=-5476` kJ/mol
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Knowledge Check

  • 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`

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