MCQ
Carbon and carbon monoxide burn in oxygen to form carbon dioxide according to the following reactions

$C + {O_2} \to C{O_2};\,\Delta H = - 394\,kJ\,mo{l^{ - 1}}$

$2CO + {O_2} \to 2C{O_2};\,\Delta H = - 569\,kJ\,mo{l^{ - 1}}$ The heat of formation of $1\,mol$ of carbon monoxide is thus .....$kJ\,mo{l^{ - 1}}$

  • A
    $ - 219$
  • $ - 109.5$
  • C
    $ - 175$
  • D
    $ - 87.5$

Answer

Correct option: B.
$ - 109.5$
(b)$C + {O_2} \to C{O_2} + 394\,kJ$.
$2C + 2{O_2} \to 2C{O_2} + 788\,kJ$….$(i)$
$2CO + {O_2} \to 2C{O_2} + 569\,kJ$….$(ii)$
$2C{O_2} \to 2CO + {O_2} - 569\,kJ$…..$(iii)$
eq. $(i) +$ eq. $(iii)$ $ = -109.5 \,kJ\,mol^{-1.}$

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