The reaction A 2 + B 2 ⇌ 2 AB has an equilibrium constant K c = 1.5. The following diagrams represent reaction mixtures containing A 2 molecules (red), B 2 molecules (blue), and AB molecules. (a) Which reaction mixture is at equilibrium?

Hello everyone today. We are being given the following problem. The three diagrams below to pick three different reaction mixtures. The reaction takes place between hydrogen which is light gray molecules, and iodine which are light violet molecules and has an equilibrium continent of 45.9 at 490 degrees Celsius. And here we have the equation identify which mixture, if any is at equilibrium. So to find out if the equation is an equilibrium, we must first write our reaction quotient, which is of course I'm going to be based off the chemical equation here or the chemical reaction here and so it's gonna be the concentration of our products over the concentration of our reactant. And so we have our products being H. I. Or hydrogen iodide. And that's going to be simply H. I in brackets And that coefficient of two is gonna be placed as an exponent for our reactant. We have hydrogen gas which is just a church too, and iodine, which is just I two. And that is our reaction quotient. And so we must make note of a couple of rules as well. If our reaction quotient is less than our value of K, then we have the reaction proceeding to the right, so the reaction proceeds to the right. If Q equals K, we have equilibrium. And if Q is greater than K, the reaction's going to proceed to the left. And so if we look at our first reaction here, We see that we have five molecules of hydrogen gas. Remember hydrogen gas is light gray. So we have 12345 light gray molecules. We must also make note that we have three iodine molecules. So we have three iodine molecules here and last but not least. We have our two molecules of hydrogen iodide to H. I molecules. We're gonna go and plug that into the Q. Value. So at Q we said that Q is equal to R. H. I. Which is gonna be two, we're gonna square that And that's gonna be placed over five and 3 to give us a value of 0.27. The equilibrium constant is 45.9 per given in that question stem. And so we see here that Q is less than K. No equilibrium for the first one, we're gonna go ahead and continue this for the 2nd and 3rd 1. So for the second one we see that we have our H two being light gray molecules and so we have 123456 and seven for iodine are violet or purple molecules. We have 123 and four. And last but not least for our H. I. We have and nine. And so we can go ahead and plug that into our que equation as well. So we have our nine squared we're gonna place that over seven times four and that gives us 2.9. Once again our Q is going to be less than K. So no equilibrium. Now we're going to be at our last and final flask here for our H two or hydrogen gas. We have gray molecules, we have for our already I. D. We have 123 and last, but not least for H I. R. Hydrant I died. We have 12345678 molecules of those. And now we can plug that into our Q equation. Once again, we're gonna have eight squared over two times three to us. The value of 10.7. We see here that once more Q is less than K. So we have no equal Librium, so none of these reaction tanks are going to have equilibrium, so no equilibrium for any of these reactions here and with that we've answered the question. I hope this helped. And until next time.

Ch.15 - Chemical Equilibrium

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Brown 15th Edition

Ch.15 - Chemical Equilibrium

Problem 9a

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Chapter 15, Problem 9a

The reaction A₂ + B₂ ⇌ 2 AB has an equilibrium constant K_c = 1.5. The following diagrams represent reaction mixtures containing A₂ molecules (red), B₂ molecules (blue), and AB molecules. (a) Which reaction mixture is at equilibrium?

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Step 1: Understand the concept of equilibrium. In a chemical reaction, equilibrium is the state where the concentrations of all reactants and products remain constant over time. The equilibrium constant (Kc) is a measure of the ratio of the concentrations of products to reactants at equilibrium.

Step 2: Identify the balanced chemical equation for the reaction. In this case, it is A2 + B2 ⇌ 2 AB. This tells us that for every one molecule of A2 and B2 that reacts, two molecules of AB are produced.

Step 3: Understand the equilibrium constant expression for this reaction. It is given by Kc = [AB]^2 / ([A2][B2]). This expression tells us that at equilibrium, the square of the concentration of AB divided by the product of the concentrations of A2 and B2 is equal to Kc.

Step 4: Look at the diagrams provided. The reaction mixture that is at equilibrium will have concentrations of A2, B2, and AB such that when substituted into the equilibrium constant expression, the result is equal to the given Kc value of 1.5.

Step 5: Compare the number of molecules (which is proportional to concentration) of A2, B2, and AB in each diagram to the balanced chemical equation and the equilibrium constant expression. The diagram that satisfies the equilibrium constant expression with Kc = 1.5 is the one at equilibrium.

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Key Concepts

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

Chemical Equilibrium

Chemical equilibrium occurs when the rates of the forward and reverse reactions are equal, resulting in constant concentrations of reactants and products. In the context of the given reaction, A2 and B2 combine to form AB, and at equilibrium, the concentrations of A2, B2, and AB remain unchanged over time.

Equilibrium Constant (Kc)

The equilibrium constant, Kc, quantifies the ratio of the concentrations of products to reactants at equilibrium for a given reaction at a specific temperature. For the reaction A2 + B2 ⇌ 2 AB, Kc = [AB]^2 / ([A2][B2]). A Kc value of 1.5 indicates that at equilibrium, the concentration of AB is greater than that of A2 and B2, suggesting a tendency towards product formation.

Le Chatelier's Principle

Le Chatelier's Principle states that if a system at equilibrium is disturbed by changes in concentration, temperature, or pressure, the system will adjust to counteract the disturbance and restore a new equilibrium. This principle helps predict how the equilibrium position will shift in response to changes in the concentrations of A2, B2, or AB in the reaction mixture.

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Le Chatelier's Principle

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When lead(IV) oxide is heated above 300°C, it decomposes according to the reaction, 2 PbO2(𝑠) ⇌ 2PbO(𝑠) + O2(𝑔). Consider the two sealed vessels of PbO2 shown here. If both vessels are heated to 400°C and allowed to come to equilibrium, which of the following statements is or are true? a. There will be less PbO2 remaining in vessel A than in vessel B.

Textbook Question

When lead(IV) oxide is heated above 300°C, it decomposes according to the reaction, 2 PbO₂(𝑠)⇌2PbO(𝑠)+O2(𝑔). Consider the two sealed vessels of PbO₂ shown here. If both vessels are heated to 400°C and allowed to come to equilibrium, which of the following statements is or are true?

b. The solid left at the bottom of each vessel will be a mixture of PbO₂(𝑠) and PbO(𝑠).

Textbook Question

The diagram shown here represents the equilibrium state for the reaction A2(𝑔) + 2B(𝑔) ⇌ 2AB(𝑔). (a) Assuming the volume is 2 L, calculate the equilibrium constant 𝐾𝑐 for the reaction.

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Textbook Question

Suppose that the gas-phase reactions A → B and B → A are both elementary reactions with rate constants of 4.7×10⁻³ s⁻¹ and 5.8×10⁻¹ s⁻¹, respectively. (b) Which is greater at equilibrium, the partial pressure of A or the partial pressure of B?

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Textbook Question

The equilibrium constant for the dissociation of molecular iodine, I₂(𝑔) ⇌ 2 I(𝑔), at 800 K is 𝐾_𝑐= 3.1×10⁻⁵. (b) Assuming both forward and reverse reactions are elementary reactions, which reaction has the larger rate constant, the forward or the reverse reaction?

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The reaction A2 + B2 ⇌ 2 AB has an equilibrium constant Kc = 1.5. The following diagrams represent reaction mixtures containing A2 molecules (red), B2 molecules (blue), and AB molecules. (a) Which reaction mixture is at equilibrium?

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Key Concepts

Chemical Equilibrium

Equilibrium Constant (Kc)

Le Chatelier's Principle

The reaction A₂ + B₂ ⇌ 2 AB has an equilibrium constant K_c = 1.5. The following diagrams represent reaction mixtures containing A₂ molecules (red), B₂ molecules (blue), and AB molecules. (a) Which reaction mixture is at equilibrium?