Question

A 28.7 mL sample of 0.383 M ethylamine, C₂H₅NH₂, is titrated with 0.213 M nitric acid.

After adding 21.5 mL of nitric acid, the pH is .

Use the Tables link in the References for any equilibrium constants that are required.

Answer 1

pkb = 3.2 for C H₂NH₂ mmol = molarity in M) ( volume in mL) mmol of C₂ H₂ NHg = (0.38) (28.7 mmol = 10.9921mmel mmol of 4No = (0.2131(21.5) mmol. = 4.8795 mmo ICE table C, H, NH₃ NO₂ I (mme c (mman Emmal) C. Hg NH₃ + HNO - 10.9921 4.5795 - 4.5795 - 4.5795 6.4126 weak bare +4.5795 4.5795 salt Weak bare C, H, NHg and salt c. Hs NH NO are. prerent at equilibrium so they will for a basic buffer Henderson - Hasselbalch equation for basic buffer. pot = pky + lop [talt] (weak base ) por= pkb + Log (mmel of salt mmal of weak bare pOH = pkt + log (mmal of Cats NHg No mmol of C. Hq NH2 (pon 3.2 + log ( 4.5795 1 6.4.2G por = 3.05 pH: 14-pot = ph= 14-3.05 pH = 10.95 an To.96