Question

A 10.0 mL sample of 0.75 M CH₃CH₂COOH(aq) is titrated with 0.30M NaOH(aq) (adding NaOH to CH₃CH₂COOH). Determine which region on the titration curve the mixture produced is in, and the pH of the mixture at each volume of added base.

K_a of CH₃CH₂COOH is 1.3 × 10⁻⁵.

Henderson–Hasselbalch equation: p H = p K a + log ⁡ [ b a s e ] [ a c i d ]

Part a):

1) After adding 18.0 mL of the NaOH solution, the mixture is                            [ Select ]                       ["before", "after", "at"]         the equivalence point on the titration curve.

2) The pH of the solution after adding NaOH is                             [ Select ]                       ["7.00", "5.30", "4.48", "8.70"]         .

Part b):

3) After adding 25.0 mL of the NaOH solution, the mixture is                            [ Select ]                       ["after", "before", "at"]         the equivalence point on the titration curve.

4) The pH of the solution after adding NaOH is                            [ Select ]                       ["4.62", "9.11", "9.38", "7.00", "4.89"]         .

Part c):

5) After adding 30 mL of the NaOH solution, the mixture is                            [ Select ]                       ["after", "before", "at"]          the equivalence point on the titration curve.

6) The pH of the solution after adding NaOH is                            [ Select ]                       ["4.56", "7.00", "11.18", "12.57"]         .

Answer 1