Question

Use the References to access important values if needed for this question A 27.9 mL sample of 0.255 M trimethylamine, (CH3)3N, is titrated with 0.342 M hydrobromic acid. After adding 7.57 mL of hydrobromic acid, the pH is Use the Tables link in the References for any equilibrium constants that are required. Submit Answer Retry Entire Group 8 more group attempts remaining

Answer 1

Use the References to access important values if needed for this question. A 27.9 mL sample of 0.255 M trimethylamine, (CH3)3N, is titrated with 0.342 M hydrobromic acid. After adding 7.57 mL of hydrobromic acid, the pH is 10.0 Use the Tables link in the References for any equilibrium constants that are required. Submit Answer Retry Entire Group 8 more group attempts remaining mmoles of base = 27.9x 0.255 = 7.1145 mmoles of acid = 0.342 x 7.57 = 2.5889 B + H+ ----------> BH+ 7.1145 2.5889 4.5256 0 2.5889 pH = pka + log (B/BH+] pH = 9.80 + log (4.5256/2.5889) pH = 10.04

A 22.6 mL sample of 0.256 M diethylamine, (C2H3)2NH, is titrated with 0.397 M hydrobromic acid. The pH before the addition of any hydrobromic acid is 12.1 Use the Tables link in the References for any equilibrium constants that are required. Submit Answer Retry Entire Group 8 more group attempts remaining B + H2O --------------> BH+ + OH- 0.256-X 6.9 x 10^-4 = x^2 / 0.256-X x^2 + 6.9 x 10^-4 x - 1.77 x 10^-4 x = 0.0130 pOH = 1.89 pH = 12.1