Predict the sign of ΔS sys for each of the following processes: (b) Gaseous Cl 2 dissociates in the stratosphere to form gaseous Cl atoms.

Identify the type of process: The dissociation of Cl 2 into Cl atoms is a decomposition reaction, where a single molecule breaks down into simpler substances.. Consider the molecular complexity before and after the reaction: Initially, there is one type of molecule, Cl 2 . After the reaction, there are individual Cl atoms.. Analyze the change in the number of particles: The dissociation of Cl 2 results in an increase in the number of gaseous particles. One Cl 2 molecule produces two Cl atoms.. Relate the change in particle number to entropy: An increase in the number of gas particles generally leads to an increase in entropy (\(\Delta S > 0\)) because there are more ways to arrange and distribute the energy among the particles.. Predict the sign of \(\Delta S_{\text{sys}}\): Since the number of particles increases, the system's entropy likely increases, indicating that \(\Delta S_{\text{sys}}\) is positive.

Predict the sign of ΔS sys for each of the following processes: (b) Gaseous Cl 2 dissociates in the stratosphere to form gaseous Cl atoms.

Hey everyone, we're asked, what is the sign of the change in entropy of our system? One hydrogen gas dissociates to form hydrogen atoms first. Let's go ahead and write out our reaction here. So we have our hydrogen gas and this is going to dissociate into our hydrogen atoms. And in order to balance this out, we would add a coefficient of two prior to our hydrogen atoms. And as we've learned in previous lessons, a change in entropy that is greater than zero means that our entropy increases and a change in entropy that is less than zero means our entropy decreases. So looking at our reaction, we can see that we had an increase in the number of gas molecules and because we have an increase in the number of gas molecules, this means that we had an increase in entropy. So our answer here is going to be our change in entropy of our system is going to be positive and this is our final answer. Now, I hope that made sense. And let us know if you have any questions

Ch.19 - Chemical Thermodynamics

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Brown 14th Edition

Ch.19 - Chemical Thermodynamics

Problem 42b

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Chapter 19, Problem 42b

Predict the sign of ΔS_sys for each of the following processes: (b) Gaseous Cl₂ dissociates in the stratosphere to form gaseous Cl atoms.

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Identify the type of process: The dissociation of Cl2 into Cl atoms is a decomposition reaction, where a single molecule breaks down into simpler substances.

Consider the molecular complexity before and after the reaction: Initially, there is one type of molecule, Cl2. After the reaction, there are individual Cl atoms.

Analyze the change in the number of particles: The dissociation of Cl2 results in an increase in the number of gaseous particles. One Cl2 molecule produces two Cl atoms.

Relate the change in particle number to entropy: An increase in the number of gas particles generally leads to an increase in entropy (\(\Delta S > 0\)) because there are more ways to arrange and distribute the energy among the particles.

Predict the sign of \(\Delta S_{\text{sys}}\): Since the number of particles increases, the system's entropy likely increases, indicating that \(\Delta S_{\text{sys}}\) is positive.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Entropy (ΔS)

Entropy, denoted as ΔS, is a measure of the disorder or randomness in a system. In chemical processes, an increase in the number of gas molecules typically leads to an increase in entropy, as gases have higher disorder compared to solids or liquids. Understanding how changes in the state of matter affect entropy is crucial for predicting the sign of ΔS.

Dissociation of Gases

Dissociation refers to the process where a compound breaks down into its constituent atoms or simpler molecules. In the case of gaseous Cl2 dissociating into Cl atoms, the reaction increases the number of gaseous particles in the system. This increase in the number of particles generally contributes to a positive change in entropy (ΔS > 0).

System vs. Surroundings

In thermodynamics, it is essential to distinguish between the system (the part of the universe being studied) and the surroundings (everything else). The change in entropy of the system (ΔSsys) reflects the disorder within the system itself. For the dissociation of Cl2, the increase in gaseous Cl atoms signifies an increase in the system's entropy, leading to a positive ΔSsys.