Question

using the thermodynamic information in the aleks data tab, calculate the standard reaction entropy of the following chemical reaction:
$s_8(s, \text{rhombic}) + 24f_2(g) \
ightarrow 8sf_6(g)$
round your answer to zero decimal places.
$\square \frac{\text{j}}{\text{k}}$

Explanation:

Step1: Recall the formula for standard reaction entropy

The formula for the standard reaction entropy ($\Delta S^{\circ}$) is $\Delta S^{\circ}=\sum nS^{\circ}(\text{products})-\sum mS^{\circ}(\text{reactants})$, where $n$ and $m$ are the stoichiometric coefficients of products and reactants respectively, and $S^{\circ}$ is the standard molar entropy.

Step2: Identify the reactants and products with their stoichiometry

• Reactants: $S_8$ (s, rhombic) with coefficient 1, $F_2$ (g) with coefficient 24.
• Products: $SF_6$ (g) with coefficient 8.

Step3: Look up standard molar entropies (from ALEKS Data tab, values are typically: $S^{\circ}(S_8, s, \text{rhombic}) = 167.8\ \frac{\text{J}}{\text{mol·K}}$, $S^{\circ}(F_2, g)=202.8\ \frac{\text{J}}{\text{mol·K}}$, $S^{\circ}(SF_6, g)=291.8\ \frac{\text{J}}{\text{mol·K}}$)

Step4: Calculate the entropy of products

$\sum nS^{\circ}(\text{products})=8\times S^{\circ}(SF_6, g)=8\times291.8 = 2334.4\ \frac{\text{J}}{\text{K}}$

Step5: Calculate the entropy of reactants

$\sum mS^{\circ}(\text{reactants})=1\times S^{\circ}(S_8, s)+24\times S^{\circ}(F_2, g)=1\times167.8 + 24\times202.8=167.8+4867.2 = 5035\ \frac{\text{J}}{\text{K}}$

Step6: Calculate $\Delta S^{\circ}$

$\Delta S^{\circ}=2334.4 - 5035=-2700.6\approx - 2701\ \frac{\text{J}}{\text{K}}$ (rounded to zero decimal places)

Answer:

-2701