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What is the equilibrium constant for the following reaction and determine if reactants or products are favored

Jules Bruno
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now that we've seen Example one. Let's look, at example too now example to is gonna talk about our equilibrium constant when we're given different acid association constant and what we need to realize here. This is blending Hess's law with acid base chemistry. Remember, has his law. They give us known amounts for certain equations and then they ask us to find the missing Delta H or care, whatever it is for another equation. So he was saying, What is the equilibrium? Constant? So what? It's k for this for this equation cake for the following reaction and determine if reactant or products are favored. Alright, so here I tell you that the K A or acid association constant of H C N is 4.9 times 10 to the negative 10. So here we're gonna say of this equation, it's equal to K equals 4.9 times 10 to the negative and then the acid association off. We're going to say that this is called Cloris Acid HCL 02 course acid has a k off 1.1 times 10 to the negative, too. All right, so we're gonna have to manipulate the ones with known K values. So they match this top equation here. So remember, in Hess's law, what we're gonna do is we're gonna go compound by compound and see what we find them. Here We have HC n as a reactant and there's one mole. If we look down on the other two bottom equations, here goes eight. CN also has a reacting. They both look exactly the same. Which would mean you don't wanna do anything to this equation right here. You leave it alone because this h c N already matches up perfectly with this H c n Next we're gonna look to see where do we see Cielo? Too Negative. It's a reactant here. But over here it's a product. So what does that mean we do? That means we have to reverse the reaction. Your reactions become products and your products will become react INTs, So reverse it. So this becomes Cielo to minus a quiz plus h +30 positive. A quiz gives me a check Cielo to a quiz plus h +20 acquis. And when we dealt with Delta h of the past, if we reverse the reaction that would reverse the sign for Delta H. But now we're no longer dealing with Delta H. We're dealing with K. So here it's not the same operation here. When we reverse the reaction, we actually get the inverse for K. So now the new K is going to be 1/ 0.1 times 10 to the negative, too. So that's our new answer this guy manipulated. So it is gone, and then we'll notice if you keep going, See? And negative is right here. Matches up perfectly. H C l 02 matches perfectly with this HCL 02 So we're done. What we have to do next is we have to get rid of intermediates, intermediates or compounds that look alike. Except in one reaction. It's a reactant. And in another reaction, it's a product they cancel out. So here we're gonna say who are intermediates while we have H 30 plus here as a reactant. And it cancels out with this H 30 plus over here. That's a product. Okay, so they're gone. Who else is an intermediate here? We have water as a product here. We have water as a reactant. They cancel out then, are you going to do is bring down everything that didn't get canceled out. So the HCM comes down, the Cielo to minus comes down, the CN negative comes down and the HCL 02 comes down just and it doesn't matter to the order. I write them as long as they're on the correct side. And look, we just regenerated the equation we're looking for. And since we're gonna need a little bit more room, guys, I'm gonna actually remove myself from the image just for the last minute or so. All right. So as you notice, we just regenerated the equation we had up here, so we know we did it correctly, but now we have to find its equilibrium. Constant. Are you going to stay here now is the equilibrium constant just equals this k A value times this k value. So we're gonna say cake equals 4.9 times 10 to the negative times 1/1 0.1 times 10 to the negative, too. So equals 4.45 times 10 to the negative eight. So that will be our equilibrium. Constant. So we've answered half the question so far. So what's the next part. The next part is I ask you are reactant or products favored. So remember this is gonna require us remembering a few rules that we saw several chapters back. So remember, we're going to stay here if your cake is greater than one than products and the four direction are favored. But here we have the opposite. Here are cake is less than one. So that means reactant and the reverse reaction are favored. So those are the things that we can say. And if K e q equals one, they're gonna say products and reactant air both favored, and you're at equilibrium. Okay, So again, this takes a little bit of Hess's law and applies it to our new concepts of K in K B. So just remember, if they give you an equation with an unknown K value, you have to manipulate the other ones so that they give you that same equation you're looking for in the first place. That's all we had to do here, match things up, cancel out intermediates, then multiply the case. If you reverse the reaction, then that becomes the reciprocal for K. So just remember those principles You go to guide yourself two questions like this