Question

A mixture of two moles of carbon monoxide and a mole of oxygen in a closed vessel is ignited to convert the carbon monoxide to carbon dioxide. If $\Delta$H is the enthalpy change and $\Delta$E is the change in internal energy, then:

• A. $\Delta H>\Delta E$
• B. $\Delta H<\Delta E$
• C. $\Delta H=\Delta E$
• D. the relationship between $\Delta H$ and $\Delta E$ depends on the capacity of the vessel

Answer 1

Answer: (B)

$\Delta H<\Delta E$

Formation of ${CO}_2$ from $CO$ is an exothermic reaction (heat is evolved from the system), i.e. energy is lowered. Thus, an exothermic reaction occurs spontaneously on account to decrease in enthalpy of the system.

Mathematically,

$2CO+O_2\to {2CO}_2$

Since, $\Delta H=\Delta E+\Delta nRT$

where $\Delta n$ is the change in the number of moles.

Here,$\Delta n=2-3=-1$

So, $\Delta H=\Delta E-RT$

So, $\Delta H<\Delta E$

So, option B is correct