Volume of base (mL)	pH of solution
0	1.24
2	1.26
4	1.28
6	1.31
7	1.33
8	1.34
9	1.36
10	1.39
10.5	1.4
11.2	1.42
11.6	1.43
12	1.45
12.5	1.47
13	1.5
14	1.54
15	1.58
17	1.65
19.2	1.79
21	1.97
22	2.07
23	2.23
24	2.54
24.5	2.7
25	3.26
25.5	9.72
28	11.4
31	11.7
34	11.86
37	11.97
40	12.04
42	12.07
45	12.12

Given that both HCl is a strong acid and NaOH is a strong base the equivalence point would be at a pH of 7. The volume of the NaOH added at the equivalence point can be determined through observing the graph, which is at 25mL.

Calculating the concentration of HCl

2. Titration of unknown, plot the PH vs.

Volume of base (mL)	pH of solution
0	1.44
1	1.45
2	1.46
3	1.47
4	1.49
5	1.5
5.7	1.52
7	1.54
7.9	1.57
9.2	1.6
10	1.62
11	1.64
13	1.73
15	1.81
18	1.98
20	2.15
22	2.38
24	2.98
25	6.79
26	10.97
27	11.31
28	11.49
29	11.6
31	11.74
32	11.8
34	11.91
37	12.01
40	12.08
42	12.11
45	12.15

From the above graph; the pH at an equivalence point is 7.52 as well as a volume of NaOH titrated to get to this equivalence point is 22.5mL.

· Calculating the concentration of the unknown acid.

Titration is the method for calculating the concentration of the solution of unknown morality for the number of moles for the substance is given in the samples. Titration is a process of adding just sufficient acid to neutralize a sample of base, or vice versa. A solution to be added, regularly from a burette, is known as a titrant. An objective is to calculate a concentration unknown acid.2 In this lab experiments the sample of HCL acid as the acid substance plus the NaOH as the base substance, where the HCL concentrations is unknown, and the concentration of unknown acid is also not given , 0.1002M HCL concentration of unknown acid. There is some error in this lab experiments, like use more than acid volume to titrate the solution of NaOH, where the volume has passed at the end point, the volume is uses more than the needed. To solve this problem, we create sure the volumetric flask is totally dry and clean.

In this lab experiments there are few recommendations, in order to obtain the accurate reading of the data and the value. Various errors that take place in a lab one of them being an inaccuracy of the burette reading.

The main point is, standard solutions which is used must be hundred percent pure plus the room temperature should be stable, and also it is preferable to used the dried standard material before dilute and weighting. The second one is, the molecular weight of the of the unknown acid should be considered, then compare them with theoretical value of the molecular weight of the unknown acid.

Conclusion of Identification of an unknown acid by pH titration

It is concluded that, by determining the value the p value was determined by taking the negative log of the K_A value. This pvalue can be compared with the pvalues of acetic acid plus its derivative that were given.

Acid	pK_Avalue
Acetic acid	4.76
Monochloroacetic acid	2.87
Dichloroacetic acid	1.35
Trichloroacetic acid	0.66

The pvalue of the unknown acid was calculated to be 1.28. By comparing the pvalues of the unknown acid to the pvalues given above table a closest value would be of Dichloroacetic acid with a pvalue of 1.35. The resulting difference between these values is 0.07; the difference was due to many errors that occurred in the lab one of them being the inaccuracy of the burette reading. Since a large part of the titration was titrating the solution by one drop at a time, accurate burette reading was hard to obtain.

Learning Objectives of Identification of an unknown acid by pH titration

In this lab experiment the learning objectives of lab is,

We learn that how to calculate the concentration of the unknown acid,

And the p is the value of the unknown acid.

We also learnt that Titration of HCL, and the plot the PH vs. Titration of

unknown, plot the PH vs.

References of Identification of an unknown acid by pH titration

1.	Silberberg. M.S. Chemistry: The Molecular Nature of Matter and Change, 6th ed.; McGraw-Hill: New York, 2012.
2.	Schullery, S. E.; et.al. Titration of an Unknown Acid; experiment; Eastern Michigan University.