Experiment 20.docx - Experiment 20 pH Titration of Cola...

Experiment 20
pH Titration of Cola Drinks
October 27th, 2017
CHEM 1212K
Section B05
TA: Iramofu Dominic
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Data and Results

A. Standardization of NaOH
Table 1. Standardization of NaOH
Trial
Mass KHP
(g)
Volume NaOH Solution
(mL)
[NaOH] (mol/L)
1 0.065 31.00 0.010278
2 0.067 33.50 0.009804
Mean [NaOH] (mol/L) 0.010041
B. Titration of Cola Sample
Table 2. Initial Parameters of Titration
Volume of Cola (mL) 20
Initial pH 2.31
Table 3. Data for Titration of Cola
Volume of
titrant (mL)
pH DpH DV (ml) DpH/DV
Avg. V of
titrant (mL)
0.00 2.31 0.04 1.00 0.04
1.00 2.35 0.05 1.00 0.05 0.50
2.00 2.40 0.05 1.00 0.05 1.50
3.00 2.45 0.05 1.00 0.05 2.50
4.00 2.50 0.05 1.00 0.05 3.50
5.00 2.55 0.08 1.00 0.08 4.50
6.00 2.63 0.08 1.00 0.08 5.50
7.00 2.71 0.10 1.00 0.10 6.50
8.00 2.81 0.07 1.00 0.07 7.50
9.00 2.88 0.71 3.00 0.24 8.50
12.00 3.59 0.46 1.00 0.46 10.50
13.00 4.05 0.68 1.00 0.68 12.50
14.00 4.73
0.64 1.00 0.64 13.50
15.00 5.37 0.50 1.00 0.50 14.50
16.00 5.87 0.30 1.00 0.30 15.50
17.00 6.17 0.08 1.00 0.08 16.50
18.00 6.25 0.09 1.00 0.09 17.50
19.00 6.34 0.12 1.00 0.12 18.50
20.00 6.46
0.06 0.50 0.12 19.50
20.50 6.52 0.14 1.00 0.14 20.25
21.50 6.66 0.03 0.50 0.06 21.00
22.00 6.69 0.05 0.50 0.10 21.75
22.50 6.74 0.14 1.00 0.14 22.25
23.50 6.88 0.09 0.50 0.18 23.00
24.00 6.97 0.04 1.00 0.04 23.75
25.00 7.01 0.04 1.00 0.04 24.50
26.00 7.05
0.16 1.00 0.16 25.50
27.00 7.21 0.06 0.50 0.12 26.50
27.50 7.27 0.04 1.00 0.04 27.25
28.50 7.31 0.12 0.50 0.24 28.00
29.00 7.43 0.12 0.50 0.24 28.75
29.50 7.55 0.07 0.50 0.14 29.25

30.00 7.62 0.16 0.50 0.32 29.75
30.50 7.78 0.15 1.00 0.15 30.25
31.50 7.93 0.11 0.50 0.22 31.00
32.00 8.04 0.08 0.50 0.16 31.75
32.50 8.12 0.21 0.50 0.42 32.25
33.00 8.33 0.17 0.50 0.34 32.75
33.50 8.50 0.18 0.50 0.36 33.25
34.00 8.68 0.30 1.00 0.30 33.75
35.00 8.98 0.12 0.50 0.24 34.50
35.50 9.10 0.14 0.50 0.28 35.25
36.00 9.24 0.06 0.50 0.12 35.75
36.50 9.30 0.14 1.00 0.14 36.25
37.50 9.44
0.08 0.50 0.16 37.00
38.00 9.52 0.07 1.00 0.07 37.75
39.00 9.59 0.04 0.50 0.08 38.50
39.50 9.63 0.06 1.00 0.06 39.25
40.50 9.69 0.05 2.00 0.03 40.00
42.50 9.74 0.04 1.00 0.04 41.50
43.50 9.78 0.07 2.00 0.04 43.00
45.50 9.85 0.07 1.00 0.07 44.50
46.50 9.92 0.00 0.00 0.00 46.00
[H
3
PO
4
] in Original Cola Sample (mol/L) 1.60E-02
Plot 1: Titration Curve with Approximate First Derivative
0.00 5.00 10.00 15.00 20.00 25.00 30.00 35.00 40.00 45.00 50.00
0.00
2.00
4.00
6.00
8.00
10.00
12.00
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
Average Volume of Titrant (ml)
pH Delta pH/Delta V
Table 4. Determination of K
a
Values
K
Graphical Analysis Literature Values
V
1/2
(mL) p K
a
K
a
p K
a
K
a
K
a1
6.25 2.63 2.34E-03 2.15 7.08E-03

K
a2
16.125 5.87 1.35E-06 7.2 6.31E-08
p K
a1