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?

Video transcript

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.