Question

CHEM 1211L La Man -Page CHEM 1211L Lab Manual - Page 6 Post-Lab Questions 1. List experimental factors that might lead to a high % difference between titrations 2. In a titration of a standardized NaOH solution with an unknown acid solution, what assumption would have to be made in order to calculate the concentration of the acid solution? (Write this in the form of a testable hypothesis) 3 How does the molarity of acetic acid you determined compare to the reported concentration? (Vinegar contains roughly 5 grams of acetic acid per 100 ml of solution) Based on your data, can you prove or disprove your hypothesis? Explain.

help answer questions 1 and 2

Answer 1

1) There can be a large number of reasons for high% error in titration:

a) Failure to rinse pipete before taking each solution may lead to the combination of desired solution with some previous solution and cause errors.

b) inability to judge endpoints: This may cause fluctuation in values.

c) Uncleaned glasswares.

d) Error in concentration of solutions prepared.

e) Other human errors.

2) On titrating NaOH with a strong acid like Hcl , it is assumed that all the solution is dissociated. The dissociation is assumed based on whaether acid is strong or weak.

Also the concentration of water is taken as one while finding out PH.