The standard heats of formation at 298 K for C Cl_(4)(g), H_(2)O(g), CO_(2)(g) and HCl (g) are - 25.5, -57.8, -94.1 and -22.1 kcal per mole respectively. Calculate DeltaH^(@) at 298 K for the reaction, C Cl_(4)(g)+2H_(2)O(g) to CO_(2)(g)+4HCl(g)

The standard heats of formation at 298 K for C Cl_(4)(g), H_(2)O(g), C

1.	The standard heats of formation at 298 K for C Cl_(4)(g), H_(2)O(g), CO_(2)(g) and HCl (g) are - 25.5, -57.8, -94.1 and -22.1 kcal per mole respectively. Calculate DeltaH^(@) at 298 K for the reaction, C Cl_(4)(g)+2H_(2)O(g) to CO_(2)(g)+4HCl(g)
Answer» Solution :GIVEN that, (i) `C(s)+2Cl_(2)(g) to C Cl_(4) (g),DeltaH^(0)=-25.5kcal` (ii) `H_(2)(g)+(1)/(2)O_(2)(g) to H_(2)O(g),DeltaH^(0)=-57.8kcal` (iii) `C(s)+O_(2)(g) to CO_(2)(g),DeltaH^(0)=-94.1kcal` (iv) `(1)/(2)H_(2)(g)+(1)/(2)Cl_(2)(g) to HCl(g),DeltaH^(0)=-22.1kcal` `CO_(2)` and HCl in eqn. (iii) and (iv) RESPECTIVELY are on the same sides as in the REQUIRED EQUATION, while `c cl_(4)` in Eqn. (i) and `H_(2)O` in Eqn. (ii) are on the opposite sides in the required equation. Hence applying, `[-Eqn. (i)-2xxEqn.(ii)+Eqn.(iii)+4xxEqn.(iv)]`, we get, `C(s)-2Cl_(2)(g)-2H_(2)(g)-O_(2)(g)+C(s)+O_(2)(g)+2H_(2)(g)+2Cl_(2)(g)` ` to -c cl_(4)(g)-2H_(2)O(g)+CO_(2)(g)+4HCl(g),` `DeltaH^(0)=-(-25.5)-(2xx-57.8)+(-94.1)+(4xx22.1)` or `c cl_(4)(g)+2H_(2)O(g) to CO_(2)(g)+4HCl(g),Delta^(0)=-41.4kcal`