Question

pH pH Volume of NaOH added, ml 0.00 mL Volume of NaOH added, ml 13.00 mL 1.96 13.15 1.00 mL 2.55 14.00 mL 13.24 2.00 mL 2.88 15.00 mL 13.38 3.00 mL 3.05 16.00 mL 13.49 4.00 mL 3.25 Click or tap here to enter text. Click or tap here to enter text. 5.00 mL 3.36 Click or tap here to enter text. Click or tap here to enter text. 6.00 mL 3.49 Click or tap here to enter text. Click or tap here to enter text. 7.00 mL 3.68 Click or tap here to enter text. Click or tap here to enter text. 8.00 mL 3.93 Click or tap here to enter text. Click or tap here to enter text. 9.00 mL 4.01 Click or tap here to enter text. Click or tap here to enter text. 10.00 mL 4.15 Click or tap here to enter text. Click or tap here to enter text. 11.00 mL 12.90 Click or tap here to enter text. Click or tap here to enter text. 12.00 mL 13.01 Click or tap here to enter text. Click or tap here to enter text.
using the data table find the following

Answer 1

Answer

Equivalence point in the pH curve                    = 10.0 mL

Half the volume to reach the equivalence point = 5.0 mL

Explanation

[For the sake of accuracy in result, equivalence point obtained from derivative graph, not from primary graph]

Volume of NaOH added, V, mL	pH	$\Delta$pH	$\Delta$V	$\Delta$pH/$\Delta$V
0.0	1.96	0.59	1	0.59
1.0	2.55	0.33	1	0.33
2.0	2.88	0.27	1	0.27
3.0	3.05	0.20	1	0.20
4.0	3.25	0.11	1	0.11
5.0	3.36	0.13	1	0.13
6.0	3.49	0.19	1	0.19
7.0	3.68	0.25	1	0.25
8.0	3.93	0.08	1	0.08
9.0	4.01	0.14	1	0.14
10.0	4.15	8.75	1	8.75
11.0	12.90	0.11	1	0.11
12.0	13.01	0.14	1	0.14
13.0	13.15	0.09	1	0.09
14.0	13.24	0.14	1	0.14
15.0	13.38	0.11	1	0.11
16.0	13.49

Primary graph

Volume of NaOH vs pH 16 14 12 10 pH 8 6 4 2 0 0 5 10 15 20 Volume of Naoh, mL

Derivative graph

The sudden increase in volume of NaOH against $\Delta$ pH/$\Delta$V, gives the equivalence point of pH curve. Here it is 10.0 mL. Whereas, half the volume to reach equivalence point is given by

Half the volume to reach eq. point =

Equivalencepoint 2

                                = 10.0/2

                                = 5.0 mL

Volume of NaOH vs ΔpH/ΔV 10 8 6 ΔpH/Δν 4 2 O 5 10,0 mL 10 15 20 -2 Volume of NaoH, mL