Potentiometric Acid Base Titration Lab Report

Data:

Beakers #123
KHP amounts (g)0.82110.85670.7533
Expected volume of NaOH (mL)40.4342.1937.10

[NaOH] = 0.09943M

Expected volume of NaOH in beaker # 1:

0.8211g of KHP x x x = 40.43mL

Beaker #1:

Volume of NaOH (mL)pH
0.003.75
2.433.88
4.294.01
6.184.16
8.274.28
10.014.36
12.194.47
14.284.57
16.094.64
18.054.73
20.024.81
22.134.93
24.084.97
26.255.05
28.295.16
30.325.27
32.175.39
34.105.52
36.085.73
38.276.11
41.5610.39
43.4710.79
45.2310.90
47.3411.06
49.0111.15
50.3411.22

Graph 1: The shining dot is the equivalence point (41.56,10.39) of beaker 1

Beaker # 2:

Volume of NaOH (mL)pH
0.003.90
2.014.01
4.034.13
6.024.25
7.994.34
10.124.43
12.244.53
14.194.61
16.214.69
18.054.75
20.014.82
22.084.90
24.154.98
26.195.05
28.215.15
30.075.24
32.115.34
34.175.46
36.055.61
38.195.81
40.176.24
41.387.44
41.518.29
41.839.32
41.929.33
42.029.79
42.179.92
42.3110.10
42.4510.15
42.5710.23
44.5310.80
46.5711.02
48.6111.13
50.0211.19

Graph 2: The shining dot is the equivalence point (41.51,8.29) of beaker 2.

Beaker # 3:

Volume of NaOH (mL)pH
0.003.91
2.033.99
4.154.15
6.074.27
9.574.48
12.134.60
14.024.68
16.074.77
18.014.84
20.064.93
22.125.01
24.235.12
26.095.22
28.135.33
30.135.46
32.105.62
34.005.86
36.056.42
36.216.49
36.336.56
36.456.68
36.586.75
36.757.05
36.907.09
38.057.54
38.237.93
38.478.33
38.789.76
39.0110.74
39.1510.76
39.4310.77
39.8210.79
40.1711.00
42.0111.13
44.0711.18
47.8711.28
50.0711.34

Graph 3: The shining dot is the equivalence point (39.01,10.47) of beaker 3.

Observations:

Both of KHP and NaOH solutions are colorless solutions. Adding an indicator to solution that have both of solutions under some conditions causes make it pink. Having a pink color is a sign that means most of KHP was react with NaOH.

Expected Vs Measured:

Beaker#Expected equivalence pointMeasured equivalence point
140.4341.56
242.1941.51
337.1039.01

Since this experimented based on human estimation, there is a big chance to have high percent error. In trial 1, the percent error was 2.795% which is high. Adding 3mL instead of 2 drops of NaOH was the main reason to have high percent error. Trail 2 has the lowest percent error which is 1.612%. This is reasonable since it is the only trail that had done as it planned to be. Forgetting to add an indicator was the main problem in trail 3. The percent error was 5.148% which is to high and the equivalence point probably a number less than 39.01mL.

Percent error = | Measured – Expected| x 100% / Expected

Percent error (trail 1) = | 41.56 – 40.43| x 100% / 40.43 = 2.795%

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