Question

able 3: Trial 1 Data
Syringe reading (mL) Citric Acid Added (mL) Ph
30 00 13.1
29 1 12.5
28 2 12.1
26 4 11.57
24 6 11.01
22 8 10.6
18 12 10.02
16 14 9.87
14.3 15.7 9.5
13.9 16.1 9
13.5 16.5 8.2
13 17 7.8
12.5 17.5 7.6
12 18 7.5
11 19 7
10.5 19.5 6.8
10 20 6.55
9.5 20.5 6.2
8.5 21.5 5.59

Trial 2 Data

Syringe reading (mL)	Citric Acid Added (mL)	pH
30	0.0	13.1
28	2	12.22
26	4	11.6
24	6	11
22	8	10.5
18	12	10
16	14	9.8
14.5	15.5	9.6
13.9	16.1	9.2
13.7	16.3	8.8
13.5	16.5	8.3
13	17	7.84
12.5	17.5	7.5
12	18	7.3
11	19	7.01
10.5	19.5	6.82
10	20	6.45
9.5	20.5	6.21

above are the two trial information

(a) According to your experimental data, what volume of C6H8O7 represents the half-equivalence (a.k.a. half-neutralization) point in this titration?

(b) What is the pH of the solution at the half-neutralization point?

Answer 1

Plot the graph between a pH vs volume of citric acid.

From the graph, we first obtained an equivalence point at P^H of 9.5.

we know that

At the half-equivalence point, the PH value is equal to the P^Ka and also the volume of a half-equivalence point is exactly one-half of the volume of the equivalence point.

So, a volume of the equivalence point = 15.7 ml at PH = 9.5- obtained from graph)

therefore the volume of the half-equivalence point = 15.7/2 = 7.85ml. ----->volume at half neutralization point.

or we can assume the volume of the half-equivalence point around = 8ml ( for more simplification)

then Ph = 10.6

b) pH should be 10.65 at a volume of the half-equivalence point = 7.85ml

for trial 2

Same procedure

Plot graph between PH and volume of citric acid added

From the graph, we obtain the volume of equivalence point = 15.5 ml at PH = 9.6.

So, the volume of half-equivalence point = 15.5/2 = 7.75

PH at half equivalence point = 10.563 ( obtained from the graph).

the graph for

trial 1

for trial 2

The equivalence point is the point in a titration where the amount of titrant added is enough to completely neutralize the analyte solution.