The enthalpies of combustion of carbon and carbon monoxide are –393.5 and –283 kJ mol-1 respectively. The enthalpy of formation of carbon monoxide per mole is
110.5 kJ
676.5 kJ
–676.5 kJ
–110.5 kJ.
As we learnt in
Hess's Law -
The total amount of heat change in a chemical reaction is the same whether the reaction is carried out in one or several steps by one or more methods.
- wherein
i) C + O2 CO2 H = -393.5KJ mol-1
ii) CO + O2 = - 283.0 kJ mol-1
operating (i) and (ii)
Option 1)
110.5 kJ
this is incorrect option
Option 2)
676.5 kJ
this is incorrect option
Option 3)
–676.5 kJ
this is incorrect option
Option 4)
–110.5 kJ.
this is correct option
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