Chemical Thermodynamics Question 308

Question: The enthalpies of combustion of carbon and carbon monodie are -393.5 and -283 kJ mol-1 respectivley. The enthalpy of formation of carbon monoxide per mole is [AIEEE 2004]

Options:

A) $ -676.5,kJ $

B) $ 676.5,kJ $

C) $ 110.5,kJ $

D) $ -110.5,kJ $

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Answer:

Correct Answer: D

Solution:

$ C(s)+O_2(g)\to CO_2(g) $

$ \Delta H=-393.5,KJ,mo{{l}^{-1}} $ -..(i) $ CO(g)+1/2O_2(g)\to CO_2(g) $

$ \Delta H=-283,KJ,mo{{l}^{-1}} $ -..(ii)

On substracting equation (ii) from equation (i) We get

$ C(s)+O_2(g)\to CO(g) $ ; $ \Delta H=-110.5,KJ,mo{{l}^{-1}} $

The enthalpy of formation of carbon monooxide per mole $ =-110.5,KJ,mo{{l}^{-1}} $



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