Class notes

III.
Buffer Capacity
A. Objectives:
1. Calculate the pH of a solution where the buffer capacity has been
exceeded.
2. Choose among alternatives for the best buffer system for a given pH. n ÿ ÿ ,ÿ
Q
2V_a t+ÿl fÿ f4
pH:
B. Two important points: z ÿ===ÿ-'--- ÿ C,/ÿ .- ÿ kÿJ ]
1. The pH is determined by the ratio oÿ,[HA]/[A- ] 2ÿ ÿ[-ÿÿ !/k,ÿ r ÿ ÿ,Aÿ'
2. The buffer capacity is detennined by t'h-ÿnSaÿnltuÿ des of [I-IA] and [A-]. ÿZÿ
The more you have, the more strong acid or strong base that can be 0
neutralized.
C. Example: Adding a strong acid to a buffered solution
1. Calculate the change in pH that occurs when 0.010 mole gaseous HC1
is added to 1.0L of each of the following solutions: ÿÿ dkÿl'ÿ
Solution A: 5.00 M HC2H302 and 5.00 M NaC2H302 I, ÿ N t ;- ÿ
Solution B: 0.050 M HC2H302 and 0.050 M NaC2H302
2. Solution:
# ÿ + io9 ( rÿ h zn ÿaÿ, cÿ, Lo aÿ3czJ=
£r4 g.zÿ430ÿ-ÿJ . , crNCx1430zÿ
: - Ioq ÿ¢, ÿ ×/0-s') :
-ÿ eÿ43 oÿ_ eÿ) eoÿplÿbÿ
if, Oopl
5ÿ,OIM
4b,- son ÿ ÿÿ
vSoOÿ /" , 0017=
q, vg