Page 74 - Analytical Chemistry I E-book

Problems & questions

• Calculate the pH after addition of 0.00, 5.00, 15.00, 25.00, 40.00, 45.00,
49.00, 50.00, 51.00, 55.00, and 60.00 mL of 0.10 M NaOH in the titration of
50.00 mL of 0.10 M nitrous acid HNO2 (Ka = 4.5 x 10–4).

• A 15.00 mL sample of HBr was titrated with NaOH. A volume of 34.8 mL of
0.1250 M NaOH was required to reach the equivalence point.

- Determine the molar concentration of HBr.
- What is the pH at the equivalence point?
- Draw the titration curve. Name a good indicator to use.
• A 15.00 mL sample of hydrofluoric acid (HF) (MW = 20) (Ka = 6.8 x 10–4) was

titrated with 28.2 mL of 0.10 M KOH.
- Calculate molarity of hydrofluoric acid sample.
- Draw the titration curve. Give the name of a suitable indicator
- Calculate pH at the equivalence point.