Hess's Law & Equilibrium Constant K

Jules Bruno
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Hey, guys. So here we're gonna apply the thermal chemistry concept of Hess's law and applied toe are variable equilibrium, constant K. So here they tell us that the value for KP is 0.39 for the following reaction. Now they're asking is what is going to be the new KP for this new equation at the same temperature. Realize that this equation here is this same equation given to us down here. Except this second equation has been manipulated to be in this form. So let's take a look at the first equation and realize what the changes that occurred. One change that occurred waas. We reversed the reaction. No. Two was a reactant. Now it's a product and tool for is a product. Now it's a reactive. So we reversed the reaction. And remember, when you reverse the reaction, we don't switch the sign of K, we do the inverse of K. So here KP was 0.39 because we reversed, it becomes 0.39. The next thing we need to realize is that we divided this by three. So that's how it became two thirds and one third. But instead of saying dividing by three, we can say we multiplied by one third. So again, dividing by a number means you're multiplying by one over that number. Now, why do we need to talk about it in terms of multiplication? That's because whatever number we multiply our equation by becomes the power. So if you multiply by one third, that means you're taking Kate to the one third power and you're one third power just means your cube root. So you're gonna do one divided by 10.39 take the cube root of that number for some of you. You may see this on your calculator. You may see this button. So to do cube root you would hit you had three than that button, and then you would do parentheses one divided by 10.39 close parentheses for others. You may not have that button. So instead, what you should do is you should do 1. to the one third, so raise it to that power now, whichever one you do, what you get as your answer at the end would be 1. as the new K for your equation So remember, if you are are reversing the reaction, you get the reverse sign or not the riverside. If you reverse your reaction, get the reciprocal Sorry. So if you reverse your reaction, you get the reciprocal. If you multiply by a number, it becomes the power. Remember, divided by number means that you're multiplying by one over that number. So multiplication creates the power that that you've seen this attempt to do the next. Following example. If you get stuck, don't worry, just come back and take a look at how I approach that question. But let me give you guys some hits on how to do this. So just realize we have to isolate the K of this equation. And to do that we manipulate thes equations here. So if you're familiar with Hess's law, you should be able to do this. And remember what happens when you reverse the reaction or multiplied by a number. Once you've isolated each of these equations, you would multiply each one of these cases to get this missing K here, and that all seems too complicated. Just come back and take a look at how I do it