The standard enthalpiesof formation ofCO_(2)(g), H_(2)O(l)and glucose (s)at 25^(@)C are-400 kJ //mol, - 300 kJ//mol and-1300kJ//molrespectively.The standard enthalpy of combustion per gram of glucose at25^(@)C is

The standard enthalpiesof formation ofCO_(2)(g), H_(2)O(l)and glucose

1.	The standard enthalpiesof formation ofCO_(2)(g), H_(2)O(l)and glucose (s)at 25^(@)C are-400 kJ //mol, - 300 kJ//mol and-1300kJ//molrespectively.The standard enthalpy of combustion per gram of glucose at25^(@)C is
Answer» ` + 2900kJ` ` -2900kJ` ` - 16.11kJ ` `+16.11 kJ` Solution :`C_(6)H_(12)O_(6)(s)+ 6O_(2)(g)rarr6 CO_(2)(g) +6 H_(2)O(l)` `Delta_(r)H^(@)=Delta_(c) H^(@) = [ 6 Delta_(F)(CO_(2)) + 6 Delta_(f)H^(@) ( H_(2)O)]- [ Delta_(f) H^(@) ( C_(6)H_(12)O_(6)) + 6 Delta_(f) H^(@) ( O_(2))]` `= 6 xx ( - 400) + 6 ( - 300) -( - 1300)` `= -2900 kJ` `= - ( 2900)/( 180 ) kJ //g =- 16.11 kJ //g`