Question

Data Table 2: Titration Curve Values pH Value Trial 1 pH Value Trial 2 pH Value (Average) Drops NaOH Added Half- Equivalence Point Equivalence Point ? ? ? ? ? ? 0 2.5 2.5 2.5 10 4.5 4.5 4.5 20 4.5 4.5 4.5 30 4.5 4.5 4.5

Answer 1

The half-equivalence point is halfway between the equivalence point and the origin. This is the point at which the pH of the solution is equal to the dissociation constant (pKa) of the acid.

	titration curve value
Drops of NaOH added	pH value (trial 1)	pH value (trial 2)	average pH
0	2.5	2.5	2.5
10	4.5	4.5	4.5
20	4.5	4.5	4.5
30	4.5	4.5	4.5
40	4.5	4.5	4.5
50	5	5	5
60	5.5	5.5	5.5
70	6	6.5	6.25
80	12.5	13	12.75
90	13.5	13.5	13.5
100	13.5	13.5	13.5
110	14	14	14
120	14	14	14

(trial 1) 16 14 12 10 pH value (trial 1) 8 pH value (trial 1) 6 4 2 0 0 20 40 60 80 100 120 140 Drops of NaOH added

(trial 2) pH value(trial 2) 16 14 O O O 12 10 PH VALUE (TRIAL 2) 8 o © O 0 O 4 O 2 0 0 20 40 60 80 100 120 140 DROPS OF NAOH ADDED

titration curve 16 14 12 10 pH value (average) 8 6 -titration curve value 2 0 0 20 40 60 80 100 120 140 Drops of NaOH added

	The half-equivalence point pH = pKa = 4.6
pH at The half-equivalence point is in trial 1		pH at The half-equivalence point is in trial 2		average pH	pKa
4.6		4.6		4.6	4.6
pH at equivalence point is in trial 1		pH at equivalence point is in trial 2		average pH
9.25		9.75		9.5
pKa	Ka	pKa	Ka
4.6	2.51189E-05	4.6	2.51189E-05
	percentage error of pKa
approx value	exact value	error	% error
4.6	4.7	-0.021276596	2.127659574
percentage error of Ka
approx value	exact value	error	% error
2.51189E-05	1.99526E-05	0.258925412	25.89254118

pKa value = 4.6

The pKa of acetic acid is 4.7...and our pKa value = 4.6 which is closes value

so the acid is acetic acid.