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CEM125E LLINOIS INSTITUTE OF TECHNOLOGY t7: Titration Curves of Polyprotic Acids

ID: 1029753 • Letter: C

Question

CEM125E LLINOIS INSTITUTE OF TECHNOLOGY t7: Titration Curves of Polyprotic Acids Pre-lab Questions 1. What is a polyprotic acid? 2. If 10.7 mL of 0.105M NaOH is required to reach the first equivalence point a solution of citric acid(H,C.HO), how many milliliters of NaOH are required to completely neutralize this solution? 3. Derive the relationship between pH and pK, at one-half the equivalence point for the titration of a weak acid with a strong base 4. If the pH at the one-half the first and second equivalence points of a diprotic acid(H2A) is 4.20 and 7.34, respectively, what are the values for pKa and pKa? From the pKa and pKa values calculate the Ka and Ka; for this acid. 5. If the pKa of a diprotic acid is 2.90, what is the ph of a 0.10M solution of this acid that has been one-quarter neutralized? Page 3

Explanation / Answer

Ans 1 :

Acids are the species that are able to donate the proton . So when the acid contains more than one ionisable protons , it is called as polyprotic acid.

For example : H2CO3 : carbonic acid : It can donate two protons.

H3PO4 : Phosphoric acid : It can donate three protons.