I would like my work checked, and some help on question 2.D. Pre-Laboratory Assi

Question

I would like my work checked, and some help on question 2.D.

Pre-Laboratory Assignment 1. Define the following terms: a) equivalence pointles mores at the analyte binflectionppinta Cvr ve at, which chonge ·n Poi at a v d:rection of ClV occurs c) tangent buextndeJ Joes not cross it a4 that Point 2. a) Draw the structural formulae of potassium hydrogen phthalate (KHP) and of phthalic acid. Show the molar mass for each, and record the KHP molar mass in your lab notebook. HO ?? b) Using the abbreviations for phthalic acid as "H2P", the hydrogen phthalate ion as "HP"", and the phthalate ion as "pz.", write two equilibrium reactions that communicate that it is a diprotic acid: c) KHP is a salt. It contains the K+ ion, which is a spectator ion in the above equilibria. Place a circle around the reactant in the above equilibria that is present when KHP dissolves. d) When you titrate KHP, you will see only one equivalence point. How do the reactions in (b) explain why will you obtain the second acid dissociation constant of phthalic acid? 3. If in a titration of a diprotic acid you obtained 12.20 mL for the volume at the first equivalence point, at what volume would you expect the second equivalence point? WHY? a eev; vai bnce Points, anJ the equivalence egints regvire the ome alvme of base fa the a Paint volme of base to reach

Explanation / Answer

Answers are all correct

2. d) second equivalence point in phthalic acid is due to the loss of the proton from the second -COOH group, HP- goes to P^2- species (second equation in b)

Phthalic acid is a diprotic acid as shown in b) with two ionizable protons in it. Loss of the two proton results in two dissociation constants.

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