Formation of $\mathrm{NO}_{2(\mathrm{~g})}$ from $\mathrm{N}_{2(\mathrm{~g})}$ and…
Formation of $\mathrm{NO}_{2(\mathrm{~g})}$ from $\mathrm{N}_{2(\mathrm{~g})}$ and $\mathrm{O}_{2(\mathrm{~g})}$ is an endothermic process. Which of the following is true for this reaction?
$\Delta \mathrm{H}=0$
$\Delta \mathrm{H} < 0$
$\Delta \mathrm{H}=\Delta \mathrm{U}$
$\Delta \mathrm{H}>0$
Solution
$\frac{1}{2} \mathrm{~N}_{2(\mathrm{~g})}+\mathrm{O}_{2(\mathrm{~g})} \longrightarrow \mathrm{NO}_2(\mathrm{~g})$
In endothermic process heat is absorbed during the reaction.
$\Delta \mathrm{H}>\mathrm{O}$