Question

10. Assume you are carrying out the titration of 50 mL of a 0.025 M solution of acetic acid with 0.1023 M NaOH. Acetic acid has a Ka of 1.8 × 10−5 .

(a) Calculate the pH of the solution at V = 0, V = 0.3Veq, V = Veq, and V = 1.2Veq. (Veq is the equivalence point volume)

(b) If a phenolphthalein indicator was used in this titration, where would the apparent endpoint occur? Assume the apparent endpoint would occur at the end of the color range of the indicator (pH’s of 8.0-9.6).

12. The sulfate content of an unknown solution was determined through an EDTA titration. 1.00 g of anhydrous BaCl2 was added to 50.0 mL of an unknown solution buffered at a pH of 10. The resulting solution was titrated with a 0.102 M solution of EDTA, and the endpoint (using an Eriochrome black T indicator) was found to occur at a volume of 10.12 mL. The MW of BaCl2 is 208.23 g/mol.

(a) Calculate the concentration of sulfate in the sample.

(b) What would the concentration of Ba2+ be at the endpoint of the titration?

Answer 1