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When ethyne is passed through a red hot ...

When ethyne is passed through a red hot tube, then formation of benzene takes place:
`H_(f(C_(2)H_(2))(g))^(@)=230kJ" "mol^(-1)`
`DeltaH_(f(C_(6)H_(6))(g))^(@)=85kJ" "mol^(-1)`
calculate the standard heat of trimerisation of ethyne to benzene.
`3C_(2)H_(2)(g)toC_(6)H_(6)(g)`

A

205kJ `mol^(-1)`

B

605 kJ `mol^(-1)`

C

`-605kJ" "mol^(-1)`

D

`-205` kJ `mol^(-1)`

Text Solution

Verified by Experts

The correct Answer is:
C
`DeltaH_("reaction")=DeltaH_(f(C_(6)H_(6)))^(@)-3DeltaH_(f(C_(2)H_(2)))^(@)`
`=85-3(230)`
`=-605kJ" "mol^(-1)`.
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