Defn: the quantity of acid or base the buffer can accommodate without a significant pH change (more than 1 pH unit). Addition of a large amount of H O + will react with all of the A ‐ Addition of a large amount of H 3 O present so that the ratio of HA/A ‐ is greater than 10:1 After this point, the pH will change dramatically upon further addition of H 3 O + Similar story for the addition of base.
8 Calculate the pH of a 1L aqueous solution that is 0.15 M in pH After Addition of Acid to a Buffer Strong electrolytes NH 3 and 0.30 M in NH 4 NO 3 after 0.020 mol of gaseous HCl is bubbled through the solution (assume the added gas does not change the volume). From problem: [NH 3 ] initial = 0.15 M [NH 4 + ] initial = 0.30 M [HCl] initial = [H 3 O + ] initial = 0.0200 M pH Change From problem: [NH ] 0 15 M [NH 3 ] initial = 0.15 [NH 4 + ] initial = 0.30 M [HCl] initial = [H 3 O + ] initial = 0.0200 M Which component of the buffer will the H 3 O + (aq) react with, NH 4 + (aq) or NH 3 (aq)? NH 3 + H 3 O + ( l ) ⇌ NH 4 + (aq) + H 2 O(aq) Initial Change Equil. 0.15 0.020 0.30 -0.020 -0.020 +0.020 0.13 0 0.32