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....

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

From the following data, the heat of formation of Ca(OH)_(2 (g)) at 18^(@) C is ……….. Kcal : CaO_((s)) + H_(2) O _((l)) to Ca(OH)_(2 (s)) , Delta H_(18^(@) C) = -15.26 kcal " " …. (i) H_(2) O_((l)) to H_(2 (g)) + (1)/(2) O_(2 (g)) , DeltaH _(18^(@) C) = 68.37 kcal " " ... (ii) Ca_((s)) + (1)/(2) O_(2(g)) to CaO_((s)), DeltaH_(18^(@) C) = -151.80 kcal " " .... (iii)

The heat of formation of PCl_(5)(s) from the following data will be : 2P(s)+3Cl_(2)(g)to 2PCl_(3)(l), Delta H = - 151.8 Kcal and PCl_(3)(l)+Cl_(2)(g)to PCl_(5)(s) , Delta H =- 32.8 Kcal

The heat of formation of PCl_(5)(s) from the following data will be : 2P(s)+3Cl_(2)(g)to 2PCl_(3)(l), Delta H = - 151.8 Kcal and PCl_(3)(l)+Cl_(2)(g)to PCl_(5)(s) , Delta H =- 32.8 Kcal

From the following data at 25^(@)C , calculate the bond energy of O – H bond: (i) H_(2)(g) to 2H(g), Delta H_(1) = 104.2 kcal (ii) O_(2)(g) to 2O(g), DeltaH_(2) = 118.4 kcal (iii) H_(2)(g) + 1/2 O_(2)(g) to H_(2)O(g), Delta H_(3) = -57.8 k cal

From the following data at 25^(@)C , calculate the bond energy of O – H bond: (i) H_(2)(g) to 2H(g), Delta H_(1) = 104.2 kcal (ii) O_(2)(g) to 2O(g), DeltaH_(2) = 118.4 kcal (iii) H_(2)(g) + 1/2 O_(2)(g) to H_(2)O(g), Delta H_(3) = -57.8 k cal

Calculate heat of formation of KOH(s) using the following equations K(s) +H_(2)O(l) +aq rarr KOH(aq)+1//2 H_(2)(g),DeltaH =- 48.0 kcal …(i) H_(2)(g) +1//2O_(2)(g) rarr H_(2)O(l),DeltaH =- 68.4 kcal …(ii) KOH(s) +(aq) rarr KOH(aq),DeltaH =- 14.0 kcal ....(iii)