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Ch.18 - Thermodynamics: Entropy, Free Energy & Equilibrium
Chapter 18, Problem 27d

Ideal gases A (red spheres) and B (blue spheres) occupy two separate bulbs. The contents of both bulbs constitute the initial state of an isolated system. Consider the process that occurs when the stopcock is opened.
(d) Relate each of the pictures to the graph in Figure 18.11.

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1
Identify the initial and final states of the gases in the bulbs from the description and the images provided. Note the color and distribution of the spheres (red for gas A and blue for gas B) in each bulb before and after opening the stopcock.
Examine the graph in Figure 18.11 to understand how it represents the changes in properties such as pressure, volume, or temperature over time as the stopcock is opened.
Correlate the changes observed in the bulb images (distribution of red and blue spheres) with specific points or trends on the graph. For example, if the gases are mixing, look for a point in the graph where properties like pressure might stabilize as the gases reach equilibrium.
Analyze the behavior of the gases using the ideal gas law and principles of diffusion. Consider how the opening of the stopcock allows the gases to mix, leading to an equal distribution of particles and possibly a change in pressure or volume as depicted in the graph.
Discuss the implications of the system being isolated, meaning no energy or matter is exchanged with the surroundings, and how this affects the properties of the gases as shown in the graph.

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Key Concepts

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

Ideal Gas Law

The Ideal Gas Law is a fundamental equation in chemistry that relates the pressure, volume, temperature, and number of moles of an ideal gas. It is expressed as PV = nRT, where P is pressure, V is volume, n is the number of moles, R is the ideal gas constant, and T is temperature in Kelvin. Understanding this law is crucial for analyzing the behavior of gases during processes such as expansion or compression.
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Kinetic Molecular Theory

Kinetic Molecular Theory explains the behavior of gases at the molecular level, positing that gas particles are in constant, random motion and that their collisions with each other and the walls of their container result in pressure. This theory helps to understand how changes in temperature and volume affect gas behavior, particularly during the mixing of gases when the stopcock is opened.
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Kinetic Molecular Theory

Thermodynamics of Gases

Thermodynamics of gases involves the study of energy transfer and the laws governing the behavior of gases during physical processes. Key concepts include the first law of thermodynamics, which states that energy cannot be created or destroyed, and the implications of adiabatic and isothermal processes. These principles are essential for analyzing the changes in state and energy when gases A and B mix after the stopcock is opened.
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Related Practice
Textbook Question

Ideal gases A (red spheres) and B (blue spheres) occupy two separate bulbs. The contents of both bulbs constitute the initial state of an isolated system. Consider the process that occurs when the stopcock is opened.

(a) Sketch the final (equilibrium) state of the system.

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Textbook Question

Ideal gases A (red spheres) and B (blue spheres) occupy two separate bulbs. The contents of both bulbs constitute the initial state of an isolated system. Consider the process that occurs when the stopcock is opened.

(b) What are the signs ( + , - , or 0) of ∆H, ∆S, and ∆G for this process? Explain.

280
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Textbook Question

Ideal gases A (red spheres) and B (blue spheres) occupy two separate bulbs. The contents of both bulbs constitute the initial state of an isolated system. Consider the process that occurs when the stopcock is opened.

(c) How dpes this process illustrate the second law of thermodynamics?

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Textbook Question
Rank the situations represented by the following drawings according to increasing entropy.
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Textbook Question
An ideal gas is compressed at constant temperature. What are the signs ( + , - , or 0) of ∆H, ∆S, and ∆G for the process? Explain.

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Textbook Question

Consider the dissociation reaction A2(g) ⇌ 2 A(g). The following pictures represent two possible initial states and the equilibrium state of the system:

(b) What are the signs ( + , - , or 0) of ∆H, ∆S, and ∆G when the system goes from initial state 1 to the equilibrium state? Explain. Is this a spontaneous process?

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