1.

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

Answer»

`+2900 kJ`
`-2900 kJ`
`-16.11 kJ`
`+16.11 kJ`

Solution :`C_(6)H_(12)O_(6)(s)+6O_(2)(G)rarr6CO_(2)(g)+6H_(2)O(l)`
`Delta_(c)H=6xxDelta_(f)H(CO_(2))+6Delta_(f)H(H_(2)O)-Delta_(f)H(C_(6)H_(12)O_(6))`
`-6Delta_(f)H(O_(2), g)`
`=6xx(-400-300)-(-1300)-0`
=-4200+1300
=-2900kJ/mol
For one gram of glucose, ENTHALPY of combustion
`=-(2900)/(180)=-16.11 kJ//g`.


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