Question

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Answer 1

A. ΔS > 0 contributes to spontaneity.

Step-by-step explanation:

In thermodynamics, entropy (ΔS) is a measure of the disorder or randomness of a system. Spontaneity refers to whether a reaction or a process will occur on its own without the need for external intervention, such as the addition of energy.

The relationship between entropy and spontaneity is described by the second law of thermodynamics. According to this law, for a spontaneous process to occur in an isolated system (where no energy or matter exchange takes place with the surroundings), the total entropy of the system and its surroundings must increase. In other words, the entropy change of the system (ΔS) and the entropy change of the surroundings (often denoted as ΔS_surroundings) should be greater than zero when combined:

`\rightarrow \Delta S_{\text{universe}}= \Delta S_{\text{system}} + \Delta S_{\text{surroundings}} > 0`

If ΔS universe is positive, the process is spontaneous in the given conditions. So, option A is the correct answer.

`\hrulefill`Explanation of the other options:

B. ΔS does not affect spontaneity:

This statement is incorrect because, as explained above, the entropy change of a system plays a crucial role in determining the spontaneity of a process.

C. ΔS < 0 contributes to spontaneity:

This statement is incorrect. A negative entropy change (ΔS < 0) would lead to a decrease in the total entropy of the system and its surroundings (ΔS_universe < 0). Such a process would not be spontaneous in an isolated system.

D. ΔS = 0 contributes to spontaneity:

This statement is incorrect as well. If the entropy change is exactly zero (ΔS = 0), then the total entropy change of the universe would also be zero (ΔS universe = ΔS system + ΔS surroundings = ΔS + ΔS = 0). In this case, the process would be at equilibrium and wouldn't be spontaneous.

`\hrulefill`

Additional Information:

Gibbs Free Energy (ΔG): Another important concept related to spontaneity is Gibbs free energy, which combines the information from both entropy and enthalpy changes of a system. The Gibbs free energy change (ΔG) determines whether a reaction is spontaneous or non-spontaneous under constant temperature and pressure conditions. The relationship between ΔG, ΔH (enthalpy change), and ΔS (entropy change) is given by the equation:

`\boxed{\left\begin{array}{ccc}\text{\underline{Gibbs Free Energy Equation:}}\\\\\Delta G = \Delta H - T\Delta S\end{array}\right }`

Where:

• T is the temperature in Kelvin.
• If ΔG is negative, the reaction is spontaneous.
• If ΔG is positive, the reaction is non-spontaneous.