Question

3.0 M HI Unknown NaOH initial burette reading 0.2 ml 0.7 ml final burette reading 47.6 ml 37.5 ml What is the concentration of the base (NaOH) in the following titration?

Answer 1

Answer:

0.128 g sample of KHP (HKC8H4O4) required 28.54 mL of NaOH solution to reach a phenolphthalein endpoint. Calculate the molarity of the NaOH.

HKC8H4O4 + NaOH -----> NaKC8H4O4 + H2O

(0.128 g KHP)(1 mol / 204.23 g KHP ) = 6.267 x 10-4 mol KHP

(6.267 x 10-4 mol KHP)(1 mol NaOH / 1 mol KHP) = 6.267 x 10-4 mol NaOH

6.267 x 10-4 mol NaOH / 0.02854 L NaOH = 0.0220 M NaOH