How will overshooting the end point of an acid-base titration by adding too much base to KHP affect the calculated molarity of the base?
I would think you would need to add more KHP, then more base to bring it to the endpoint. So the molarity calculated should be the same.
Is that correct?
Or if you didn't correct this error, the molarity of the base would be higher than it should be.
Is that correct?
Oops, I mean the molarity would decrease because moles base / larger quantity in L = a small # therefore decreased molarity.
Correct?
I find it helpful to write each step of the procedure and see how the question affects each.
1. mols KHP = grams/molar mass
2. mols NaOH = mols KHP
3. M NaOH = mols NaOH/L NaOH
So you did steps 1 and 2 right but on 3 added too much L NaOH. That's in the denominator, too big number means too small M.
No, that is not correct. Overshooting the endpoint of an acid-base titration by adding too much base to the potassium hydrogen phthalate (KHP) solution will indeed affect the calculated molarity of the base.
During an acid-base titration, a known concentration of acid or base is reacted with an unknown concentration of the opposite reactant until a specific endpoint is reached. The endpoint is generally indicated by a color change in an indicator solution or by monitoring the pH with a pH meter. At the endpoint, the moles of acid and base are stoichiometrically equivalent.
In the case of titrating a base with KHP, KHP acts as the acid. Its molarity can be determined by titrating it with a base of known concentration until the endpoint is reached. The balanced reaction equation between KHP and the base is as follows:
KHP (acid) + Base → Salt + Water
If you add too much base past the endpoint, it means you have exceeded the stoichiometric equivalence point, and there is an excess of base present. This excess base will react with the KHP, forming additional salt and water beyond what is required by the stoichiometry of the reaction.
As a result, the excess base will artificially increase the volume of the titration, leading to an overestimate of the molarity of the base. The calculated molarity will be higher than the actual molarity because you will be dividing the moles of base by the larger volume of the titration solution.
To correct this, you would need to repeat the titration using a smaller volume of KHP or weigh a more concentrated sample of KHP to ensure that you reach the endpoint without overshooting it. By using a smaller volume of KHP and adjusting the calculations accordingly, you can obtain a more accurate molarity of the base.
In summary, adding too much base beyond the endpoint of an acid-base titration will result in an overestimation of the calculated molarity of the base. It is important to avoid overshooting the endpoint to obtain accurate results.