The standard entropy change for the reaction: SO2( g)+(1)/(2) O2( g) ⟶SO3( g) is (where S^∘ for

step 1 One equation in the question S .O2 gas plus half O2 gas makes the product S .O3 gas. And in the

The standard entropy change for the reaction:...

The standard entropy change for the reaction: $\mathrm{SO}_{2}(\mathrm{~g})+\frac{1}{2} \mathrm{O}_{2}(\mathrm{~g}) \longrightarrow \mathrm{SO}_{3}(\mathrm{~g})$ is (where $\mathrm{S}^{\circ}$ for $\mathrm{SO}_{2}$ (g), $\mathrm{O}_{2}(\mathrm{~g})$ and $\mathrm{SO}_{3}(\mathrm{~g})$ are $248.5,205$ and $256.2$ J $\mathrm{K}^{-1} \mathrm{~mol}^{-1}$ respectively) (a) $198.2 \mathrm{~J} \mathrm{~K}^{-1} \mathrm{~mol}^{-1} \quad$ (b) $-192.8 \mathrm{~J} \mathrm{~K}^{-1} \mathrm{~mol}^{-1}$ (c) $-94.8 \mathrm{~J} \mathrm{~K}^{-1} \mathrm{~mol}^{-1}$ (d) $94.8 \mathrm{~J} \mathrm{~K}^{-1} \mathrm{~mol}^{-1}$

The standard entropy change for the reaction:
$\mathrm{SO}_{2}(\mathrm{~g})+\frac{1}{2} \mathrm{O}_{2}(\mathrm{~g}) \longrightarrow \mathrm{SO}_{3}(\mathrm{~g})$ is (where $\mathrm{S}^{\circ}$ for
$\mathrm{SO}_{2}$ (g), $\mathrm{O}_{2}(\mathrm{~g})$ and $\mathrm{SO}_{3}(\mathrm{~g})$ are $248.5,205$ and $256.2$
J $\mathrm{K}^{-1} \mathrm{~mol}^{-1}$ respectively)
(a) $198.2 \mathrm{~J} \mathrm{~K}^{-1} \mathrm{~mol}^{-1} \quad$ (b) $-192.8 \mathrm{~J} \mathrm{~K}^{-1} \mathrm{~mol}^{-1}$
(c) $-94.8 \mathrm{~J} \mathrm{~K}^{-1} \mathrm{~mol}^{-1}$
(d) $94.8 \mathrm{~J} \mathrm{~K}^{-1} \mathrm{~mol}^{-1}$

Key Concepts

Standard Molar Entropy

Standard molar entropy is a measure of the randomness or disorder of a substance at a standard state (typically 1 bar pressure). It is expressed in units of joules per kelvin per mole (J K?¹ mol?¹) and provides a baseline for comparing the energy dispersal in different substances under standard conditions.

Entropy Change of Reaction

The entropy change of a reaction (?S?) is determined by taking the sum of the standard molar entropies of the products multiplied by their stoichiometric coefficients and subtracting the sum of the standard molar entropies of the reactants similarly multiplied. This concept shows how the overall disorder of a system changes as a chemical reaction progresses.

Stoichiometric Coefficients

In entropy calculations, the stoichiometric coefficients from the balanced chemical equation are used to appropriately weight the contribution of each reactant and product to the overall entropy change. This ensures that the calculation accurately reflects the proportions in which each substance participates in the reaction.

Units and Sign Conventions

Understanding the units (J K?¹ mol?¹) and sign conventions is essential; a positive entropy change indicates an increase in disorder, whereas a negative value signifies a decrease. This concept is crucial for interpreting the thermodynamic feasibility of chemical reactions and predicting how reaction conditions influence spontaneity.

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