The standard enthalpies fo formation of `CO_(2) (g), H_(2) O (1)`, and glucose (s) at `25^(@)C` are `- 400 kJ mol^(-1), - 300 kJ mol^(-)`, and `- 1300 kJ mol^(-1)`, respectively. The standard enthalply of combustion per gram of glucose at `25^(@)C` is

Options

A. `+2900kJ`
B. `-2900kJ`
C. `-16.11kJ`
D. `+16.11kJ`

Answer

C

Explanation

`C_(6)H_(12)O_(6)(s)+6O_(2)(g)to6CO_(2)(g)+6H_(2)O(l)`
`DeltaH[6Delta_(f)H_(CO_(2))+6Delta_(f)H_(H_(2)O)]-[Delta_(f)H_(C_(6)H_(12)O_(6)+6Delta_(f)H_(O_(2))]`
`=[6(-400)+6(-300)]-[-1300+0]`
`=-4200+1300=-2900kJ//mol`
Enthalpy of combustion per gram `=(-2900)/(180)=-16.11kJ//g`