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H(2)(g)+1//2O(2)(g)=H(2)O(l) , Delta H(2...

`H_(2)(g)+1//2O_(2)(g)=H_(2)O(l) , Delta H_(298 K)=-68.32` Kcal. Heat of vapourisation of water at 1 atm and `25^(@)C` is 10.52 Kcal. The standard heat of formation (in Kcal) of 1 mole of water vapour at `25^(@)C` is

A

`10.52`

B

`-78.84`

C

`+57.80`

D

`-57.80`

Text Solution

Verified by Experts

The correct Answer is:
D
`H_(2(g))+(1)/(2)O_(2(g))rarr H_(2)O_((g)) , Delta H_(f) = ?`
`H_(2(g))+(1)/(2)O_(2(g))rarr H_(2)O_((l)) , Delta H=-68.32 KCal`
`H_(2)O_((l))rarr H_(2)O_((g)) , Delta H_("Vap")=10.52 KCal`
eq(i) = eq(ii) + eq(iii)
`Delta H_(f)=(-68.32)+(10.52)`
`Delta H_(f)=-57.80 KCal mol^(-1)`
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ALLEN-THERMODYNAMICS -EXERCISE -3
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  2. The enthalpy change of a reaction does not depend on

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  13. The heat of reaction of A+(1)/(2)O(2)rarr AO is -50 K call and AO+...

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  14. C(s)+O(2)(g)rarr CO(2)(g)+94.0 K cal. CO(g)+(1)/(2)O(2)(g)rarr CO(2)...

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