Calculate the standard heat of formation of carbon disulphide (l). Given that the standard heats of combustion of carbon (s), sulphur (s) and carbon disulphide (l) are -393.3, -293.72 and -1108.76 kJ `mol^(-1)` respectively.

Options

A. `-128.02 kJ mol^(-1)`
B. `+12.802 kJ mol^(-1)`
C. `+128.02 kJ mol^(-1)`
D. `-12.802 kJ mol^(-1)`

Answer

C

Explanation

`C+2SrarrCS_(2) DeltaH=?`
`C+O_(2)rarrCO_(2)DeltaH=-393.3 kJ " ....(i)"`
`S+O_(2)rarrSO_(2)DeltaH=-293.72 kJ " ....(ii)"`
`CS_(2)+3O_(2)rarrCO_(2)+2SO_(2) DeltaH=-1108.76 kJ" ....(iii)"`
eq. (ii) `xx2+` eq. (i) - eq. (iii) - and find required result.