Predict the sign of ΔS^∘ and then calculate ΔS^∞ for each of...

Predict the sign of $\Delta S^{\circ}$ and then calculate $\Delta S^{\infty}$ for each of the following reactions. a. $\mathrm{H}_{2}(g)+\mathrm{O} \mathrm{O}_{2}(g) \longrightarrow \mathrm{H}_{2} \mathrm{O}(l)$ b. $2 \mathrm{CH}_{3} \mathrm{OH}(g)+3 \mathrm{O}_{2}(g) \longrightarrow 2 \mathrm{CO}_{2}(g)+4 \mathrm{H}_{2} \mathrm{O}(g)$ c. $\mathrm{HCl}(g) \longrightarrow \mathrm{H}^{+}(a q)+\mathrm{Cl}^{-}(a q)$

Predict the sign of $\Delta S^{\circ}$ and then calculate $\Delta S^{\infty}$ for each of the following reactions.
a. $\mathrm{H}_{2}(g)+\mathrm{O} \mathrm{O}_{2}(g) \longrightarrow \mathrm{H}_{2} \mathrm{O}(l)$
b. $2 \mathrm{CH}_{3} \mathrm{OH}(g)+3 \mathrm{O}_{2}(g) \longrightarrow 2 \mathrm{CO}_{2}(g)+4 \mathrm{H}_{2} \mathrm{O}(g)$
c. $\mathrm{HCl}(g) \longrightarrow \mathrm{H}^{+}(a q)+\mathrm{Cl}^{-}(a q)$

Key Concepts

Entropy

Entropy is a thermodynamic quantity representing the degree of randomness or disorder in a system. It is a central concept in thermodynamics, indicating how energy is distributed among the microscopic configurations of a system.

Standard Molar Entropy

Standard molar entropy refers to the entropy value assigned to one mole of a substance under standard conditions (usually 1 bar and a specified temperature, typically 298 K). These tabulated values allow us to calculate the net entropy change for chemical reactions by subtracting the sum of the entropies of the reactants from that of the products.

Phase Effects on Entropy

The state of matter plays a significant role in the entropy of a substance. Gases have much higher entropy than liquids or solids because their molecules move freely and occupy a larger volume. Thus, a change from a gaseous state to a liquid state generally results in a decrease in entropy.

Molecularity and Stoichiometry in Entropy Changes

The number of moles or molecules present in the reactants and products influences the overall entropy change. A reaction that decreases the total number of gas molecules is likely to result in a decrease in entropy, while an increase in the number of molecules, particularly gases, tends to increase entropy.

Ion Solvation Effects on Entropy

When a compound dissolves in water and dissociates into ions, the process involves the formation of a solvation shell where water molecules become more ordered around each ion. This ordering typically reduces the system's entropy significantly, even though the number of solute particles increases.

Transcript

Please give Ace some feedback