Name: 緩衝液計算 (Buffer solution calculations)
Uploaded: 2021-01-14T05:44:20.000Z
Duration: 11 min 39 s
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- [Voiceover] Let's do some buffer solution calculations

using the Henderson-Hasselbalch equation.

So in the last video I showed you how to derive

So we're talking about a conjugate acid-base pair here.

if we're gonna calculate the pH of our buffer solution,

So let's say we already know the Ka value for NH four plus

So let's get out the calculator and let's do that math.

Henderson-Hasselbalch equation right here.

plus the log of the concentration of A minus, our base.

and our concentration in our buffer solution

And that's over the concentration of our acid,

that's NH four plus, and our concentration is .20.

So this is over .20 here and we can do the math.

So the final pH, or the pH of our buffer solution,

because we're going to compare what happens to the pH

when you add some acid and when you add some base.

And we're gonna see what that does to the pH.

Let's say the total volume is .50 liters.

that will give us the concentration of sodium hydroxide.

So that's our concentration of sodium hydroxide.

And since sodium hydroxide is a strong base,

that's also our concentration of hydroxide ions in solution.

So this is our concentration of hydroxide ions,

what that's going to react with in our buffer solution.

So our buffer solution has NH three and NH four plus.

The base is going to react with the acids.

So hydroxide is going to react with NH four plus.

Let's go ahead and write out the buffer reaction here.

ammonium is going to react with hydroxide

and this is going to go to completion here.

So if NH four plus donates a proton to OH minus,

Alright, let's think about our concentrations.

So we just calculated that we have now .01 molar

So let's go ahead and write 0.24 over here.

all of that is going to react with the ammonium.

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緩衝液計算 (Buffer solution calculations)

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water

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