Question

I was wondering if anybody could explain the relationship between pH and conductivity. I performed a titration experiment based on polyprotic acids and I am trying to figure out why it is that the conductivity of my solution behaved the way it did in the experiement as the volume and pH changed. I'll provide the date just in case it helps, but even just a brief explanation would be so appreciated!

Volume	pH	Conductivity
0	1.3	23.29
0.05	1.3	23.19
0.15	1.31	23.01
0.54	1.35	22.37
1.04	1.38	21.24
1.43	1.41	20.58
1.83	1.43	19.95
2.24	1.47	19.39
2.54	1.5	18.98
3.05	1.54	18.48
3.36	1.55	18.05
3.85	1.59	17.57
4.24	1.62	17.23
4.54	1.64	16.98
4.93	1.67	16.69
5.43	1.71	16.36
5.83	1.75	16.13
6.12	1.77	15.98
6.63	1.8	15.72
7.13	1.86	15.49
7.53	1.87	15.34
7.93	1.91	15.21
8.33	1.94	15.08
8.84	1.99	14.94
9.14	2.02	14.87
9.63	2.05	14.76
10.02	2.1	14.68
10.42	2.14	14.61
10.82	2.17	14.55
11.21	2.22	14.49
11.31	2.22	14.47
11.71	2.27	14.42
12.11	2.33	14.39
12.32	2.34	14.37
12.51	2.37	14.34
12.77	2.41	14.32
12.83	2.43	14.32
12.88	2.42	14.32
12.93	2.44	14.32
12.99	2.45	14.3
13.04	2.45	14.32
13.28	2.5	14.3
13.48	2.53	14.29
13.63	2.54	14.28
13.88	2.59	14.26
14.08	2.63	14.24
14.44	2.71	14.22
14.84	2.81	14.21
15.25	2.95	14.19
15.64	3.15	14.2
16.04	3.44	14.18
16.44	4.33	14.23
16.94	5.3	14.67
17.34	5.56	15.04
17.74	5.74	15.4
18.15	5.87	15.75
18.56	5.98	16.07
18.96	6.06	16.39
19.26	6.12	16.6
19.75	6.19	16.94
20.14	6.27	17.22
20.54	6.31	17.48
21.05	6.39	17.78
21.44	6.44	17.96
21.84	6.48	18.19
22.24	6.52	18.48
22.64	6.57	18.68
22.94	6.59	18.83
23.44	6.65	19.08
23.83	6.69	19.27
24.23	6.74	19.45
24.63	6.78	19.63
25.13	6.82	19.83
25.53	6.85	19.99
25.93	6.9	20.15
26.33	6.95	20.3
26.73	7	20.44
27.12	7.04	20.56
27.52	7.08	20.71
27.93	7.12	20.82
28.31	7.17	20.92
28.71	7.22	21.06
29.1	7.28	21.14
29.5	7.34	21.27
30	7.42	21.41
30.39	7.5	21.46
30.78	7.58	21.59
31.18	7.67	21.66
31.57	7.8	21.74
31.98	7.97	21.82
32.38	8.24	21.89
32.79	8.94	21.96
33.19	11.09	22.17
33.49	11.38	22.57
33.89	11.59	22.96
34.38	11.76	23.39
34.77	11.86	23.75
35.17	11.94	24.11
35.48	12	24.37
35.98	12.06	24.79
36.38	12.12	25.1
36.78	12.16	25.43
37.07	12.18	25.66
37.57	12.23	25.97
37.96	12.26	26.33
38.36	12.29	26.64
38.77	12.32	26.93
39.06	12.34	27.14
39.56	12.36	27.48
39.82	12.38	27.66
39.87	12.38	27.69
40.22	12.4	27.95

Answer 1

Let us plot the data , we will obtain graph like this for different measurements of pH and conductivity at different volume of base added

As we can see

a) the conductivity decreases first and then it increases

This is due to neutralizaiton of acid So there will be decrease in concentration of H+ so the conductivity decreases.After neutralization of the acid the conductivity starts increasing further as the concentration of OH- starts increasing. so the change in conductivity is due to change in concentration of H+ and OH-

b) The neutralization points of polyprotic acid shows that the acid is diprotic as there are two curves in the pH graph.