Grade Maleic Acid Neutralization Mechanism - The first order of business

Grade Maleic Acid Neutralization Mechanism Questions

Below is the simulation of the titration of 50.00 mL of 0.0500 M maleic acid by 0.1000 M NaOH discussed in general terms in lecture. In this practice assignment, we willexplicitly calculate expected pH values at various points (increasing volume of titrant) in this titration. The titration curve is shown below.

10 20 30 40 50 60 mL titrant

1. The first order of business when dealing with atitration is to obtain a clear understanding of the chemistry going on in solution.

 a) Using molecular formulas, propery write out the two ionizations possible for the diprotic acid maleic acid. Label each ionization step with the appropriate numerical values of Ka1 and Ka.

b) Using molecular formulas, properly write out the two steps of the titration of the diprotic acid maleic acid with NaOH. For simplicity (and clarity), leave the spectator Na" out of the equations. point volume(s). It is obvious

2. It is important in any titration problem to first calculate the expected eguivalence from the concentrations and volumes of analyte and titrant chosen in this example (and ultimately from looking at the simulation) that the first equivalence point volume (Ve) is at 25.00 mL and the second equivalence point volume (Vez) is at 50.00 mL. This will not always be so obvious in other examples of titration curves. Therefore, SHOWW howyou would calculate that Ve1 Would be 25.00 mL and that Vez Would be 50.00 mL for this example where 50.00 mL of a 0.0500 M solution of the diprotic maleic acid is titrated by 0.1000 M NaOH.

3. Calculate the initial pH of the 50.00 mL of 0.0500 M maleic acid.

4. Calculate the pH after addition of 8.00 ml of 0.1000 MNaOH. (Recall this is in the "first buffer region" of the titration.

5. Calculate the pH halfway to the first equivalence point.

6. a) What would be the principal species in solution at the first equivalence point? b) Calculate the pH at the first equivalence point.

7. Calculate the pH halfway between the first and second equivalence points. (Recall this is in the "second buffer region" of the titration.

8.Calculate the pH when a totalof 45.00 mL of 0.1000 MNaOH has been added. (Recall this is still in the "second buffer region" of the titration.

9.a) What would be the principal species in solution at the second equivalence point? b)Calculate the pH at the second equivalence point.

10. Calculate the pH when an additional 3.00 mL of 0.1000 M NaOH is added beyond the second equivalence point.