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Henderson-Hasselbalch Equation Example 2

Jules Bruno
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Hey, guys, In this new video, we're gonna continue with our discussion and calculating Ph for a buffer. So here in this first example, it says, What is the buffet component concentration ratio, which really is just conjugate base over weak acid off a buffer that has a pH off 5.11 here, I tell you, the K of the acid is 1.30 times 10 to the negative five. Now, since we're dealing with a buffer, let's write out the Henderson Household back equation. The buffer equation so ph equals P K plus log of conjugate base over weak acid. Here, we're gonna say that the pH I tell you is 5.11 PK. Remember, PK is just simply the negative log of K. So we're gonna take the negative log of 1.30 times 10 to the negative five. When we do that, we get 4.89 Take that 4.89 Plug it in here, plus log of conjugate base over weak acid. Now, we're trying to find just this portion right here, so we just have to move everything away from it. Toe isolated. So here we're gonna say so. Track 4.89 from here. So track 4.89 from here. So we're gonna get 0.22 equals Log off. Conjugate base over weak acid. Now, remember, we need toe isolate conjugate base over weak acid. So we have to get rid of that log. How do we do that? Divide both sides by log, which is similar to doing the anti log. So all you say to yourself here is I'm doing the anti log of something. I'm dividing it by log. When I divide anything by log, it becomes 10 to that number. Okay, Now, just realize here that the sign does not change. It was positive here. It's still positive here. Taking the anti log of something does not change the sign. Now, when we take that number and plug it into our calculator, we're gonna get 166 And since this is a ratio, the answer you get is always gonna be over one. So we have 1.6 6/1. What does that mean? That means for every 1.66 conjugate base, I have one weak acid involved. So here we're basically saying that conjugate base is greater in amount than weak acid. These are all the little things you need to know. Professor could just simply say, What is the ratio of conjugate based a weak acid, you would say 1.66 to 1. Or they could ask which one is greater in amount, conjugate base or weak acid? Because the conjugate base is 1.66 while the weak acid is only one. You would say that conjugate base is greater than weak acid, and it all starts from knowing. First we're dealing with a buffer. And second, we have to use the Henderson Hasselbach equation, so we just simply have to manipulate it through algebra. Now that we've done this one, let's go to example, too.