Ozone, O 3 , decomposes to molecular oxygen in the stratosphere according to the reaction 2 O 3 (𝑔) ⟶ 3 O 2 (𝑔). Would increasing the pressure by decreasing the size of the reaction vessel favor the formation of ozone or of oxygen?

hi everyone for this problem, it reads hydrogen gas and iodine gas react to form gasses, hydrogen iodide. Would a change in pressure affect the yield of the reaction If yes, would an increase or decrease in pressure favor the formation of hydrogen iodide. Okay, so for this question we want to answer whether or not a change in pressure is going to affect the yield of our reaction. So we have a reaction that is at equilibrium and so we're dealing with outliers principle here, which tells us when we have an equilibrium or a system that's at equilibrium and a stress is put on that system. The system is going to readjust to maintain its equilibrium state and in this particular instance, our stress is a change in pressure. So we need to understand how does change in pressure affect the yield of our reaction. So the first thing we need to know is that if we have an increase in pressure, this is going to cause our reaction to want to shift to fewer moles of gas. Okay, on the other hand, if we have a decrease in pressure that is going to cause our reaction to want to shift to the side with more moles of gas to offset that. Okay, and so we want to know if an increase or decrease in pressure will favor the formation of hydrogen iodide. So let's go ahead and rewrite out our equation. So we can see what is going on. Okay, so the first thing that we want to do is see how many moles we're dealing with of reactant and product because like we said, an increase or decrease in pressure is going to favor either the fewer moles of gas or the more moles of gas on each side. So on our reactant side we have two moles. And on our product side we also have two moles. Okay. And so our change in the number of moles. So this is represented by delta N. R. Change in number of moles is zero. Okay, so what this means is pressure will not affect the equilibrium reaction. So our answer to this problem is no, a change in pressure will not affect the equilibrium yield. Okay, so that is the answer to this problem and that is the end of this problem. I hope this was helpful.

Ch.15 - Chemical Equilibrium

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Brown 15th Edition

Ch.15 - Chemical Equilibrium

Problem 67

Chapter 15, Problem 67

Ozone, O₃, decomposes to molecular oxygen in the stratosphere according to the reaction 2 O₃(𝑔) ⟶ 3 O₂(𝑔). Would increasing the pressure by decreasing the size of the reaction vessel favor the formation of ozone or of oxygen?

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Consider Le Chatelier's Principle, which states that if a dynamic equilibrium is disturbed by changing the conditions, the position of equilibrium shifts to counteract the change.

In the given reaction, 2 O_3(g) ⟶ 3 O_2(g), compare the number of moles of gas on each side of the equation.

The reactant side has 2 moles of O_3, while the product side has 3 moles of O_2.

Increasing the pressure by decreasing the volume of the reaction vessel will shift the equilibrium towards the side with fewer moles of gas to reduce the pressure.

Since the reactant side has fewer moles of gas (2 moles of O_3) compared to the product side (3 moles of O_2), the equilibrium will shift towards the formation of ozone, O_3.

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Key Concepts

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

Le Chatelier's Principle

Le Chatelier's Principle states that if a dynamic equilibrium is disturbed by changing the conditions, the system will adjust to counteract the change and restore a new equilibrium. In the context of gas reactions, increasing pressure favors the side of the reaction with fewer moles of gas, as this reduces the overall pressure.

Stoichiometry of the Reaction

The stoichiometry of a chemical reaction describes the quantitative relationship between the reactants and products. In the given reaction, 2 moles of ozone (O3) decompose to form 3 moles of oxygen (O2). This indicates that the product side has more moles of gas than the reactant side, which is crucial for understanding how changes in pressure will affect the reaction.

Effect of Pressure on Gas Reactions

The effect of pressure on gas reactions is significant because gases occupy space and their behavior is influenced by changes in volume and pressure. According to the ideal gas law, increasing pressure by reducing the volume of the reaction vessel will shift the equilibrium towards the side with fewer gas molecules, which in this case is the reactants (ozone).