From the values given for ΔH^∘ and ΔS^∘, calculate ΔG^∘ for each of the following reactions at 2

step 1 This is the problem 64 in Chapter 19. And in this question, we're going to calculate the values

From the values given for ΔH^∘ and ΔS^∘, calculate ΔG^∘ for...

From the values given for $\Delta H^{\circ}$ and $\Delta S^{\circ},$ calculate $\Delta G^{\circ}$ for each of the following reactions at 298 $\mathrm{K}$ . If the reaction is not spontaneous under standard conditions at 298 $\mathrm{K}$ , at what temperature (if any) would the reaction become spontaneous? $$ \begin{array}{l}{\text { (a) } 2 \mathrm{PbS}(s)+3 \mathrm{O}_{2}(g) \longrightarrow 2 \mathrm{PbO}(s)+2 \mathrm{SO}_{2}(g)} \\ {\Delta H^{\circ}=-844 \mathrm{kk} ; \Delta S^{\circ}=-165 \mathrm{J} / \mathrm{K}} \\ {\text { (b) } 2 \mathrm{POCl}_{3}(g) \longrightarrow 2 \mathrm{PCl}_{3}(g)+\mathrm{O}_{2}(g)} \\ {\Delta H^{\circ}=572 \mathrm{kJ} ; \Delta S^{\circ}=179 \mathrm{J} / \mathrm{K}}\end{array} $$

From the values given for $\Delta H^{\circ}$ and $\Delta S^{\circ},$ calculate $\Delta G^{\circ}$ for
each of the following reactions at 298 $\mathrm{K}$ . If the reaction is not spontaneous under standard conditions at 298 $\mathrm{K}$ , at what temperature (if any) would the reaction become
spontaneous?
$$
\begin{array}{l}{\text { (a) } 2 \mathrm{PbS}(s)+3 \mathrm{O}_{2}(g) \longrightarrow 2 \mathrm{PbO}(s)+2 \mathrm{SO}_{2}(g)} \\ {\Delta H^{\circ}=-844 \mathrm{kk} ; \Delta S^{\circ}=-165 \mathrm{J} / \mathrm{K}} \\ {\text { (b) } 2 \mathrm{POCl}_{3}(g) \longrightarrow 2 \mathrm{PCl}_{3}(g)+\mathrm{O}_{2}(g)} \\ {\Delta H^{\circ}=572 \mathrm{kJ} ; \Delta S^{\circ}=179 \mathrm{J} / \mathrm{K}}\end{array}
$$

Key Concepts

Gibbs Free Energy

Gibbs free energy is a thermodynamic potential that indicates the maximum reversible work obtainable from a process at constant temperature and pressure. It combines the effects of enthalpy and entropy, and the sign of ?G determines whether a reaction is spontaneous (negative ?G) or non-spontaneous (positive ?G).

Standard Enthalpy Change

Standard enthalpy change (?H°) is the heat absorbed or released by a system under standard conditions during a chemical reaction. It reflects the energy change associated with breaking and forming bonds and plays a crucial role in determining the overall energetics of a reaction.

Standard Entropy Change

Standard entropy change (?S°) represents the change in the disorder or randomness of a system as a reaction proceeds under standard conditions. It is a measure of the dispersal of energy and matter and influences the temperature dependence of the reaction’s spontaneity.

Temperature Dependence of Reaction Spontaneity

The dependence of reaction spontaneity on temperature is described by the equation ?G = ?H – T?S. This equation shows how the balance between enthalpy and entropy determines whether a reaction becomes spontaneous at a particular temperature, which is especially critical when ?H and ?S have the same sign.

Determining the Temperature for Spontaneity

For reactions that are not spontaneous under standard conditions, the temperature at which spontaneity is achieved can be calculated by setting ?G to zero in the equation ?G = ?H – T?S. Solving for temperature (T = ?H/?S) gives the threshold at which the entropic contribution overcomes the enthalpic term, thus switching the reaction to become spontaneous.

Transcript

Please give Ace some feedback