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. `+16.11 kJ`

Answer

C

Explanation

`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`