Verified Solution • 2025–26 Session moderate

QJEEM04Chc2b5: JEE Main 2004 Chemistry - Class 11 JEEM04Chc2b5 Solution: The enthalpies of combustion of carbon and carbon monoxide are…

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 :

Multiple Choice Options

  • A 110.5 kJ
  • B -110.5 kJ
  • C -676.5 kJ
  • D 676.5 kJ

Step-by-Step Verified Solution

(i)   C+O2⇌CO2,\left( i \right)\,\,\,C + {O_2}\rightleftharpoons C{O_2},

  ΔH=−393.5 kJmol−1\,\,\Delta H = - 393.5\,kJmo{l^{ - 1}}

(ii)   CO+12O2⇌ CO2,\left( {ii} \right)\,\,\,CO + {1 \over 2}{O_2}\rightleftharpoons\,C{O_2},

        ΔH=−283.0 kJmol−1\,\,\,\,\,\,\,\,\Delta H = - 283.0\,kJmo{l^{ - 1}}

Operating (i)−(ii),(i)-(ii), we have

C+12O2→COC + {1 \over 2}{O_2} \to CO

        ΔH=−110.5 kJmol−1\,\,\,\,\,\,\,\,\Delta H = - 110.5\,kJmo{l^{ - 1}}

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