Given that `C+O_(2)rarrCO_(2),DeltaH^(@)=-xKJ` and `2CO+O_(2)rarr2CO_(2),DeltaH^(@)=-yKJ` The enthalpy of formation of carbon monoxide will be

Options

A. `(2x-y)/2`
B. `(y-2x)/2`
C. `2x-y`
D. `y-2x`

Answer

B

Explanation

Given `C+O_(2)toCO_(2)," "DeltaH^(@)=-xkJ`………..i
`2CO_(2)to2CO+O_(2)," "DeltaH^(@)=+ykJ`…….ii
or `CO_(2)toCO+1//2CO_(2)," "DeltaH^(@)=_y//2kJ`……….iii
By adding no (i) and (iii) eq.
`C+O_(2)+CO_(2)toCO_(2)+CO+1/2O_(2)`
`C+1/2O_(2)toCO, DeltaH^(@)=y//2-x=(y-2x)/2kJ`