91Ó°ÊÓ

Thermodynamics is the study of the connections between heat, work, temperature, and energy. Thermodynamic principles specify how energy develops within a system and whether it is capable of having a positive impact on its surroundings.

Copper and oxygen combine to generate${\mathrm{Cu}}_2\mathrm{O}$. Write the reaction equation for the creation of$1$mole of${\mathrm{Cu}}_2\mathrm{O}$and balance it.

$2\mathrm{CuS}\left(\mathrm{s}\right)+\frac{1}{2}{\mathrm{O}}_2\left(\mathrm{g}\right)→{\mathrm{Cu}}_2\mathrm{O}\left(\mathrm{s}\right)$

After that, make a list of each compound${\mathrm{Δ³\S }}^{\mathrm{o}}$values:

$\begin{array}{l}{\mathrm{S}}^{∘}\left(\mathrm{Cu}\left(\mathrm{S}\right)\right)=33.1\mathrm{J}/\mathrm{mol}\mathrm{K}\\ {\mathrm{S}}^{∘}\left({\mathrm{O}}_2\left(\mathrm{g}\right)\right)=205.0\mathrm{J}/\mathrm{mol}\mathrm{K}\\ {\mathrm{S}}^{∘}\left({\mathrm{Cu}}_2\mathrm{O}\left(\mathrm{S}\right)\right)=93.1\mathrm{J}/\mathrm{mol}\mathrm{K}\end{array}$

Solve for the ${\mathrm{Δ³\S }}^{\mathrm{o}}$now as:

role="math" localid="1663360861920" $\begin{array}{c}{\mathrm{Δ³\S }}^{∘}=∑{\mathrm{n}}_{\mathrm{p}}{\mathrm{S}}^{∘}\left(\mathrm{product}\right)-∑{\mathrm{n}}_{\mathrm{r}}{\mathrm{S}}^{∘}\left(\mathrm{reactant}\right)......................\left(1\right)\\ =\left[{\mathrm{nS}}^{∘}\left({\mathrm{Cu}}_2\mathrm{O}\left(\mathrm{s}\right)\right)\right]-\left[{\mathrm{nS}}^{∘}\left(\mathrm{Cu}\right(\mathrm{s}\left)\right)+{\mathrm{nS}}^{∘}\left({\mathrm{O}}_2\left(\mathrm{g}\right)\right)\right]..............\left(2\right)\\ =\left(\left[\right(93.1\left)\right]-\left[2(33.1)+\frac{1}{2}(205.0)\right]\right)\mathrm{J}/\mathrm{K}........................\left(3\right)\\ {\mathrm{Δ³\S }}^{∘}=-75.6\mathrm{J}/\mathrm{K}...............................................................\left(4\right)\end{array}$

Therefore, the value is: role="math" localid="1663360891580" ${\mathrm{Δ³\S }}^{∘}=-75.6\mathrm{J}/\mathrm{K}$.