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From the following data, the heat of for...

From the following data, the heat of formation of `Ca(OH)_(2)(s)` at `18^(@)C` is …. Kcal.
(i) `CaO(s)+H_(2)O(l)=Ca(OH)_(2)(s) , Delta H18^(@)C=-15.26` Kcal…..
(ii) `H_(2)O(l)=H_(2)(g)+1//2O_(2)(g) , Delta H18^(@)C=68.37` Kcal….
(iii) `Ca(s)+1//2O_(2)(g)=CaO(s) , Delta H 18^(@)C=-151.80` Kcal....

A

`-98.69`

B

`-235.43`

C

`194.91`

D

`98.69`

Text Solution

Verified by Experts

The correct Answer is:
B
`Ca_((s))+O_(2(g))+H_(2(g))rarr Ca(OH)_(2) , Delta H_(f) = ?`
Desired equation = eq (iii) + eq(i) - eq (ii)
`Delta H_(f)=(-151.80)+(-15.26)-(-68.37)`
`Delta H_(f)=-235.43 KCal mol^(-1)`
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