Question

Predict the sign of for each of the following changes.

Short answer

Answer

1. The sign of$\mathbf{∆}\mathbf{S}\mathbf{°}$is Negative.
2. The sign of$\mathbf{∆}\mathbf{S}\mathbf{°}$ is Positive.
3. The sign of$\mathbf{∆}\mathbf{S}\mathbf{°}$is Negative.
4. The sign of$\mathbf{∆}\mathbf{S}\mathbf{°}$is Negative.
5. The sign of$\mathbf{∆}\mathbf{S}\mathbf{°}$is Negative.
6. The sign of $\mathbf{∆}\mathbf{S}\mathbf{°}$ is Positive.

Step-by-step solution

Step 1: Introduction to the Concept

The ratio of thermal energy to the temperature at which work cannot be done is known as entropy. It's also known as the measure of a system's molecular disarray. It has a lot of properties and state functions.

The number of microstates for a system is connected to entropy, and microstate is defined as the number of possible arrangements for the system. Entropy is affected by the phase of a substance in distinct physical states; the order of entropyis indicated by: ${\mathbf{S}}_{\mathbf{solid}}\mathbf{<}{\mathbf{S}}_{\mathbf{liquid}}\mathbf{<}{\mathbf{S}}_{\mathbf{gas}}$

With the use of the aforementioned data, the sign of the entropy should be predicted.

Step 2: Prediction of the sign of ∆S°

a)

Because equally dispersed gas molecules flow to one side of a two-sided container, the sign of entropy is negativein this situation. Because there is just one way for gas molecules to assemble themselves, this reduces positional probability. Thesign of entropy change is negative due to losses in unpredictability.

Step 3: Prediction of the sign of ∆S°

b)

Given reaction is:$\mathrm{AgCl}\hspace{0.17em}\left(\mathrm{s}\right)\to {\mathrm{Ag}}^{+}\left(\mathrm{aq}\right)+{\mathrm{Cl}}^{‐}\left(\mathrm{aq}\right)$

The sign of entropy in this example is positivesince the solid material is disintegrating into its constituent ions.As the liquid state is disordered in compared to the solid state, this leads in an increase in unpredictability. The sign of entropy change is positive due to increases in unpredictability.

Prediction of the sign of ∆S°

c)

Given reaction is:$2{\mathrm{H}}_2\left(\mathrm{g}\right)+{\mathrm{O}}_2\left(\mathrm{g}\right)\to 2{\mathrm{H}}_2\mathrm{O}\left(\mathrm{I}\right)$

Because two gases react with each other to create liquid, the sign of entropy is negative in this scenario. This reduces randomness because the liquid state is less chaotic than the gaseous state. The sign of entropy change is negative due to losses in unpredictability.

Step 5: Prediction of the sign of ∆S°

d)

Given reaction is:$\mathrm{Na}\left(\mathrm{s}\right)+\frac{1}{2}{\mathrm{Cl}}_2\left(\mathrm{g}\right)\to \mathrm{NaCl}\left(\mathrm{s}\right)$

The sign of entropy is negative in this situation because in this process, one solid and one gaseous species react to generate solid (new). This reduces randomness since the solid state is the most ordered of the three states (gaseous, liquid, and solid). The sign of entropy change is negative due to losses in unpredictability.

Prediction of the sign of ∆S°

e)

Given reaction is:$\mathrm{HCl}\left(\mathrm{g}\right)\to {\mathrm{H}}^{+}\left(\mathrm{aq}\right)+{\mathrm{Cl}}^{‐}\left(\mathrm{aq}\right)$

The sign of entropy in this example is positive because the gaseous species is dissolving into its constituent ions. As the gaseous state is more disordered than the liquid state, this leads in a decrease in randomness. The sign of entropy change is negative due to losses in unpredictability.

Step 7; Prediction of the sign of ∆S°

f)

Given reaction is:$\mathrm{KBr}\left(\mathrm{s}\right)\to {\mathrm{K}}^{+}\left(\mathrm{aq}\right)+{\mathrm{Br}}^{‐}\left(\mathrm{aq}\right)$

The sign of entropy in this example is positive since the solid material is disintegrating into its constituent ions. As the liquid state is disordered in compared to the solid state, this leads in an increase in unpredictability. The sign of entropy change is positive due to increases in unpredictability.