In these two types of titration curves, the pH changes gradually before the equivalence point, because we're going to have a buffer region that can be formed. So here we're going to take a look at the left side. In the following video we'll take a look at the other side, but let's focus on this left side first.
Here we have a weak acid strong base titration curve. We're starting off with a pH less than 7. So because the pH is less than 7 here, it would have to be the weak acid because if it was a strong base let's it would be above 7. Here we're slowly adding our strong base to it. So our strong base is the tight trend. Because we're starting out with an acid, we see that the pH is less than 7 and it increases gradually with added base.
That's because initially there's a jump in pH, but we get to a point where a buffer has been created and so there's a slow grind up in terms of our pH. This highlighted part is where our buffer region has been created. Now here, because we have something weak versus something strong, the strong species will dominate. Therefore the pH of the equivalence point would be greater than 7. So here we can see the pH is around 8:00 or so.
Now, after the equivalence point. So we're talking about. After this red dot, we're going to say the weak acid is neutralized. An excess strong base remains. We just keep adding more and more strong base even after all that weak acid has been neutralized. So This is why our pH continues to grow and and increase over time. But eventually it's going to plateau because it can't go up forever, right?
So when it comes to this weak asset, strong base titration curve, these are the key features to keep in mind when looking at a typical curve. When we have a weak acid versus a strong base, whatever, a strong will dominate since it's a base that's the strong species. It wants the pH to be above 7 at the equivalence point, right. So that's what we see, our equivalence pH greater than 7. It's around 8:00 or so here, right? So now that we've taken a look at this titration curve, click on the next video and let's look at the opposite trend.