The Foundations of Chemistry

19-6 Weak Acid/Strong Base Titration Curves 815

Figure 19-4 The titration curve for 100. mL of 0.100 M
CH 3 COOH with 0.100 MNaOH. The “vertical” section of
this curve is much shorter than those in Figure 19-3 because
the solution is buffered before the equivalence point.

Figure 19-5 The titration curve for 100. mL of 0.100 M

aqueous ammonia with 0.100 MHCl. The vertical section of

the curve is relatively short because the solution is buffered

before the equivalence point. The curve is very similar to that

in Figure 19-4, but inverted.

pH

mL NaOH added

1

0

0 102030405060708090100110120

2

3

4

5

6

7

8

9

10

11

12

Indicator

range Equivalence point

Buffered solution

(CH 3 COOH/NaCH 3 COO)

pH

mL HCl added

1

0

0 102030405060708090100110120

2

3

4

5

6

7

8

9

10

11

12

Indicator

range

Equivalence point

(NH 3 /NH 4 Cl)

Buffered solution

TABLE 19-6 Titration Data for 100.0 mL of 0.100 M CH 3 COOH with

0.100 MNaOH

mL 0.100 M mmol Base mmol Excess

NaOH Added Added Acid or Base pH

0.0 mL 0 10.0 CH 3 COOH 2.89

20.0 mL 2.00 8.00 4.14

50.0 mL 5.00 5.00 4.74

75.0 mL buffered 7.50 2.50 5.22

90.0 mL region 9.00 1.00 5.70

95.0 mL 9.50 0.50 6.02

99.0 mL 9.90 0.10 6.74

100.0 mL 10.0 0 (equivalence point) 8.72

101.0 mL 10.1 0.10 OH
 10.70

110.0 mL 11.0 1.0 11.68

120.0 mL 12.0 2.0 11.96

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