Titrations: Strong Acid-Strong Base - Online Tutor, Practice Problems & Exam Prep

Understanding the pH during a titration between a strong acid and a strong base is simplified by the fact that either can act as the titrant or titrate, with the strong species typically serving as the titrant. To determine the pH, an ICE (Initial, Change, Final) chart is utilized, which helps track the concentrations of the acid and base throughout the reaction. This process is essential in acid–base titrations, a fundamental concept in chemistry that involves the neutralization reaction between acids and bases, leading to the formation of water and a salt. Mastery of this technique is critical for accurate pH calculations in various chemical applications.

Strong Acid-Strong Base Titration

In our discussion of acid base titrations, we now take a look at the titration between a strong acid and a strong base. And luckily this happens to be the easiest type of titrations in order to calculate pH. So here we're going to say this type of titration has either the strong acid or strong base act as the titrate or titrate.

So in one reaction you could have these strong acid as a titrate and the strong base is the titrate. Or you could have another reaction where it's flipped, where the strong base is the titrate and the strong acid is the titrate, right. Because remember, the key giveaway about a titrate is that it's the strong species. If both of them are strong, you could set up your experiment where either the strong acid or strong base is the titrate.

Now here we're going to say when a strong acid and a strong base mix together, we again use an ICF chart. ICF stands for Initial change point, so we're going to see the steps necessary to find the pH when any type of strong acid mixes with any type of strong base.

Titrations: Strong Acid-Strong Base Example

Here it says calculate the pH of the solution resulting from the titration of 75 mills of 100 molar per bromic acid with 55 mills of 100 molar sodium hydroxide. So here per bromic acid represents a strong acid and sodium hydroxide represents a strong base. So here in step one, what we're going to do first is we're going to set up an ICF chart with both species set as reactants. Next, we're going to write purbromic acid here, reacting with sodium hydroxide. Since they're both strong, we're setting up an ICF truck which stands for Initial Change Equal. I'm fine equilibrium final.

Now Step 2. It says using the initial role place the given amounts in moles. So we need the moles of each. Remember, moles equals liters times molarity, so divide the mills by 1000 to change them into liters and then multiply by the respective molarities to find the moles of per bromic acid and sodium hydroxide. When we do that, we're going to get 0.0075 moles of perpetromic acid and 0.0055 moles of sodium hydroxide. Now this is important in this ICF chart. We only care about the strong acid and the strong bass. We could determine what the products are within this and where we'd have sodium or bromate and H₂O being formed, but again, we don't care about them.

And we don't care about them because water is a liquid in itself. Solids and liquids are also ignored in ICF charts. And also the ionic salt here, that's created as a product because it originates from 2 strong species, it is going to be a neutral ionic compound. So it's not going to affect or play a role in determining our pH. So that's why we really don't care about the products being formed when we're dealing with the titration between a strong acid and a strong base, All right. So we've done that using the change row. Looking at the reactants subtract from their initial amounts by the mole amount. So let's see which one is a smaller mole amount. It's this 1.055 subtracts from both, meaning we have zero strong bass left, but we still have some strong acid remaining.

Now, using the final rule, determine the concentration of the remaining strong species. Divide its final moles by the total volume used in the chemical reaction. So who's left per bromic acid is what's left behind and and we have to divide it by the total volume. What's the total volume? Well, we used 75 mills here and 55 mills here. Added together that's 130 mills and dividing it by 1000 changes it into liters. So when we do that we're going to get 0.01538 molar for per bromic acid. So that's the concentration of our strong acid. Now recall that the hydronium ion concentration and hydroxide ion concentration are equal to the concentration of strong acids and bases respectively.

So if strong acid remains its H plus concentration, we use its H plus concentration to find pH. If strong base remains, then we use its OH minus concentration to find POH. Remember that pH plus POH gives us 14. That pH itself equals negative log of H₃O plus or H plus, and POH is the negative log of OH minus. So we just said that the H concentration is equal to the concentration of our strong acid. So we'd say our H plus concentration is equal to 0.01538 molar. Because of that we can find our pH. PH equals negative log of H plus so negative log of this 0.01538 molar. So when we plug that in, we get 1.81 as our final pH for this solution.

Calculate the pH of the solution resulting from the mixing of 175.0 mL of 0.250 M HNO₃ with 75.0 mL of 0.200 M Ba(OH)₂.

• A. 1.26
• B. 1.86
• C. 1.36
• D. 1.57

Calculate the pH of the solution resulting from the titration of 110.0 mL of 0.300 M HCl with 330.0 mL of 0.100 M LiOH.

• A. 1.5
• B. 7.0
• C. 8.5
• D. 10.0

Here’s what students ask on this topic:

What will be the pH at the equivalence point for a strong acid-strong base titration?

The pH at the equivalence point for a strong acid-strong base titration will be approximately 7. This is because strong acids and strong bases completely dissociate into their ions in water, producing hydrogen ions ($H^{+}$) and hydroxide ions (${\mathrm{OH}}^{-}$) respectively. At the equivalence point, the number of moles of hydrogen ions equals the number of moles of hydroxide ions, resulting in the formation of water ($H_{2}O$). Since water has a neutral pH of 7, the solution at the equivalence point will also be neutral if the titration is performed at room temperature and there are no other substances in the solution that could affect the pH. Keep in mind that this is true for titrations carried out in aqueous solutions under standard conditions.

When the hydronium concentration equals the hydroxide concentration in a strong acid - strong base titration, then the ______________ has been reached?

When the hydronium concentration equals the hydroxide concentration in a strong acid-strong base titration, then the equivalence point has been reached. This is the point at which the amount of acid equals the amount of base during the titration process. At the equivalence point, the number of moles of hydrogen ions (H⁺) from the acid is equal to the number of moles of hydroxide ions (OH^-) from the base, resulting in a neutral solution, typically with a pH of 7.00 at 25°C. However, the actual pH at the equivalence point can vary depending on the strengths of the acid and base used. In the case of a strong acid-strong base titration, the pH will be neutral at the equivalence point because both the acid and base completely dissociate in water.