Calorific value of hydrogengas is - 143 kJ g^(-1). The standard enthalpy of formation of H_(2)Owill be

Calorific value of hydrogengas is - 143 kJ g^(-1). The standard enthal

1.	Calorific value of hydrogengas is - 143 kJ g^(-1). The standard enthalpy of formation of H_(2)Owill be
Answer» `- 143 kJ mol^(-1)` ` + 143 kJ mol^(-1)` ` - 286 kJ mol^(-1)` `+ 286kJ mol^(-1)` Solution :Calorificvalue is the heat producedby COMBUSTION of 1 G of the FUEL, i.e., `H_(2)+(1)/(2)O_(2) rarr H_(2)O i.e., 1 g` of `H_(2)`on combustion producesheat `=143 kJ` `:. `1 MOLE , i.e., 2 g `H_(2)` will produce heat`= 286kJ` This is also `Delta_(f)H^(@) ` for `H_(2)O`i.e. `Delta_(f)H^(@) = - 286 kJ mol^(-1)`