Calculate heat of the following reaction at constant pressure, F_(2)O(g)+H_(2)O(g)rarrO_(2)(g)+2HF(g) The heats of formation of F_(2)O(g),H_(2)O(g) and HF(g) are 5.5 kcal-57kcal and -64 kcal repectively.

Calculate heat of the following reaction at constant pressure, F_(2)O

1.	Calculate heat of the following reaction at constant pressure, F_(2)O(g)+H_(2)O(g)rarrO_(2)(g)+2HF(g) The heats of formation of F_(2)O(g),H_(2)O(g) and HF(g) are 5.5 kcal-57kcal and -64 kcal repectively.
Answer» Solution :GIVEN that, (i) `F_(2)(g)+(1)/(2)O_(2)(g) to F_(2)O(g),DeltaH=-5.5kcal` (ii) `H_(2)(g)+(1)/(2)O_(2)(g) to H_(2)O(g),DeltaH=-57.8kcal` (III) `(1)/(2)H_(2)(g)+(1)/(2)F_(2)(g) to HF(g),DeltaH=-64.2kcal` `F_(2)O` and `H_(2)O` in EQNS. (i) and (ii) and in the equation given in the problem are on the opposite sides, while HF in Eqn. (iii) and in the equation given in the problem is on the same sides. THUS applying, `[-Eqn. (i) - Eqn.(ii)+2xxEqn. (iii)]`, we get `-F_(2)(g)-(1)/(2)O_(2)(g)-H_(2)(g)-(1)/(2)O_(2)(g)+H_(2)+F_(2)(g) to ` `-F_(2)O(g)-H_(2)O(g)+2HF(g),` `DeltaH=-5.5-(-57.8)+2xx(64.2)` or `F_(2)O(g)+H_(2)O(g) to O_(2)(g)+2HF(g),DeltaH=-76.1kcal.`