Strong Titrate-Strong Titrant Curves - Online Tutor, Practice Problems & Exam Prep

In strong acid-strong base titrations, the titration curve exhibits a characteristic sigmoidal shape, indicating a sharp pH change at the equivalence point where the amount of titrant equals that of the titrate. When titrating a strong acid with a strong base, the pH starts low and increases sharply until reaching the equivalence point, marked by a pH of 7, signifying neutralization. Beyond this point, excess titrant causes the pH to rise gradually until it levels off. Conversely, titrating a strong base with a strong acid starts with a high pH that decreases until the equivalence point, also at a pH of 7, after which excess titrant lowers the pH until it plateaus. In both scenarios, the equivalence point pH reflects the neutralization of the strong acid or base, demonstrating the strength and complete reaction of the titrants.

Strong Acid-Strong Base Titration Curve

You were going to say that in these two types of titration curves, both the titrate and titrate represent a strong acid or base. Here we're going to pay attention to the left side 1st and in the following video we'll take a look at the right side. All right. So here, let's just focus on the left side. In this one, it represents a strong acid, strong base titration curve.

We can see here that our titrate, which is it? Well, we're starting out at a pH that's much lower than 7. So in this case, our titrate would have to be a strong acid. As we begin to add strong base to it, we see that the pH is increasing over time. So our tight rent would have to be a strong base. Now here the pH starts below 7 and we see there's a sharp increase as we add base and we can see around 60 mL of our strong base being added. That's what we have, the steepest climb in terms of our pH.

Now here the equivalence point is this red spot right here, which is the dead center portion of the steepest climb. We can see that at that point the pH is equal to 7. Now here we're going to say after the equivalence point. So after that red dot, the strong acid is neutralized and X has strong base remains. So at this point we'll get to the equivalence point. All of the strong acid has been completely neutralized by the strong base. But since we keep adding more and more base, we're going to have some excess base remaining. That's why it continues to increase, but eventually it will level off.

So here we see a gradual leveling off around just under pH of 13. So here when we're dealing with a strong acid, strong base titration curve, the first thing discussed would be our titrate. It's being titrated by this titrate of the strong base. And doing this gives us the sigmoidal shape of our titration curve. And we see that it starts up at a low pH and eventually gets to a higher pH. So now that we've seen this type of sigmoidal curve, click on the next video and let's look at the right side or flipping roles and seeing how that curve will look.

Strong Base-Strong Acid Titration Curve

Now let's take a look at a strong base strong acid titration curve. We can see here that this also has a sigmoidal shape, but it's going the opposite direction. We can see that we're starting out at a pH that's well above 7. Since we're starting out a pH that's well above 7, that must mean our titrate is a strong base. And here we're adding our titrant over time and that's causing a decrease in our pH. So our type trend here would be a strong acid.

So here we can see that our pH starts above 7 since we have a strong base to begin with and it decreases sharply with added acid. Now here we look at the steepest drop, the steepest drop in terms of RPH. It happens here gives us this red dot, which is our equivalence point. It too would give us a pH equal to seven at the equivalence point. So keep this in mind. When both the titrate and titrate are strong, the pH will be equal to seven at the equivalence point, like regardless of who's the titrate and who's the titrate, because again, it's based on strength. Since they're both strong, it's kind of like a draw. So their pH is equal to 7 at the equivalence point.

Now after the equivalence point. So we're talking about this portion here. We see that the strong base has been completely neutralized and access strong acid remains. So when we get to the equivalence point, all of these strong acid has destroyed all of the strong base, but we continue to add more and more strong acid. So that's why our pH continues to drop. Eventually it will level off and we see here that it's leveling off around a pH of 1.

So just remember, in both cases we have a sigmoidal shape because both the app does titrate and titrate are strong species. Because they're both strong, the pH is equal to 7 at the equivalence point, right? So just keep in mind the similarities between these two types of titration curves.

Strong Titrate-Strong Titrant Curves Example

Here it says consider the titration of 100 mills of 0.500 molar hydrobromic acid solution with 120 MLS of 0.450 molar potassium hydroxide solution. Which species would be an excess? All right, so there's two ways we can approach this question. One way is we could figure out what the equivalence volume of our titrate will be. So let's say I made this the titrate. Then we can say that M⁢acid⁢times⁢V⁢acid=⁢M⁢base⁢times⁢V⁢base, and we could calculate the volume of our base to reach the equivalence point.

If the volume we calculated is less than this, and that means Koh is an excess because we've gone beyond our equivalence volume. So let's just do it that way. Then we're going to look at another way we can approach the same question. So here we say we have 500 molar of hydrochromic acid and then 100 MLS. Then we have 0.450 molar of potassium hydroxide, and we're looking for its equivalence volume. Divide both sides by 0.450 molar and we get our equivalent volume for our strong baits as being 11.1 milliliters.

So that's how much strong base we need to add to get to the equivalence point. We have a volume that's even greater than that, which would mean that Koh would be in excess. So Koh is our species. That will be in essence. Another way we could attempt this question is to remember that moles equals leader times molarity. If we divide both these volumes by 1000, we get liters of each of means multiply, so I've multiplied them by their molarities.

Doing this would give me 0.500 moles of HBR and then multiplying the leaders times molarity of this would give me 0.0540 moles of Koh. This is also telling me that, hey, we have more Koh than HBR, more moles. So Koh again would be in excess. So again, two different ways you can approach this type of question. If they're asking you to figure out which one is an access, but they're giving you the volumes of both and the molarity of both, make either one of the tight print and then try to figure out its equivalence volume.

If the equivalence volume you calculated is lower than what they're giving to you, then you're in excess. You could also calculate the moles of each which everyone has. Greater moles would be the one in excess, right. So take those two approaches, you'll find the answer. In this particular case, the answer is option B.

Which combination would give a pH = 7.0 at the equivalence point?

a) HNO₃ and NH₃                      b) HCl and NH₄⁺                        c) HC₂H₃O₂ and NaOH               d) HBr and NaH

• A. HNO₃ and NH₃
• B. HCl and NH₄⁺
• C. HC₂H₃O₂ and NaOH
• D. HBr and NaH

Here’s what students ask on this topic:

Which titration curve corresponds to the titration of a strong monoprotic acid (analyte) with a strong base (titrant)?

A titration curve that corresponds to the titration of a strong monoprotic acid with a strong base typically shows a very steep and rapid increase in pH as the equivalence point is approached. This is because both the acid and base fully dissociate in water, leading to a complete neutralization reaction.

At the beginning of the titration, the pH starts out low due to the presence of the strong acid. As the strong base is added, the pH gradually increases. As you get closer to the equivalence point, where the amount of acid initially present has been almost neutralized by the base added, the pH rises more sharply.

At the equivalence point, the solution contains only the salt and water, and the pH will be around 7, indicating a neutral solution. After the equivalence point, adding more base will cause the pH to rise rapidly again, this time due to the excess strong base in the solution.

The curve will be relatively symmetrical around the equivalence point, reflecting the rapid change in pH that occurs in a small volume of titrant addition. The vertical section of the curve is much steeper compared to titrations involving weak acids or bases, which have more gradual slopes due to incomplete dissociation.

What is the characteristic pH-titrant curve for the titration of a strong acid by a strong base?

The pH-titrant curve for the titration of a strong acid by a strong base typically features a very steep and distinct vertical section, representing a rapid pH change, which occurs at the equivalence point. This is where the amount of the strong base added is stoichiometrically equivalent to the amount of strong acid present in the solution.

At the beginning of the titration, the pH starts out low due to the strong acid's high concentration. As the strong base is added, the pH gradually increases until it nears the equivalence point. At this juncture, the pH rises very sharply with the addition of a very small volume of base. Once the equivalence point is passed, the curve levels out again, showing a slower increase in pH as the solution becomes increasingly basic.

The equivalence point for a strong acid-strong base titration typically occurs at a pH of about 7, indicating a neutral solution, because the products of the reaction are water and a salt that does not affect the pH. The curve is symmetrical around the equivalence point in this type of titration.

Which graph best represents the titration of a strong base by a strong acid?

The titration of a strong base by a strong acid is best represented by a graph showing the pH of the solution as a function of the volume of acid added. On this graph, you would see a sharp, vertical rise in the pH at the equivalence point, where the amount of acid added is stoichiometrically equivalent to the amount of base present.

At the beginning of the titration, the pH starts high because the solution is basic. As you add the strong acid, the pH decreases gradually. However, as you approach the equivalence point, the pH drops very rapidly. Once you've added just enough acid to neutralize the base, any additional acid will cause a more gradual decrease in pH again.

The resulting graph will have a characteristic "L" shape, with the vertical part of the "L" representing the rapid change in pH at the equivalence point and the base of the "L" showing the initial and final gradual changes in pH.