Moderate

(∆H−∆U) for the formation of carbon monoxide (CO) from its elements at 298 K is: (R = 8.314 J K−1 mol−1)

Correct answer: D. −1238.78 J mol−1

A. 1238.78 J mol−1
B. −2477.57 J mol−1
C. 2477.57 J mol−1
D. −1238.78 J mol−1

Explanation

C(s) + ½O(g) → CO(g) ∆H = ∆U + ∆ngRT (∆H − ∆U) = ∆ngRT= 1/2 x 8.314 x 298 = −1238.78 J mol−1

Last updated 1 September 2026

About Enthalpy

Enthalpy is the heat content of a system measured at constant pressure, and its change indicates whether a reaction or physical process is endothermic or exothermic. The topic covers state functions, enthalpy diagrams, standard enthalpy of formation, combustion and neutralisation, and the relationship between ΔH and internal energy change.

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(∆H−∆U) for the formation of carbon monoxide (CO) from its elements at 298 K is: (R = 8.314 J K−1 mol−1)

About Enthalpy

Practise Thermochemistry and Energetics of Chemical Reactions

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