Please use the below data that I obtained from my lab and please kindly help with questions 2-5 and the observations/conclusion/interpretation of results please.

The aim of this experiment is to identify the defining characteristics of acids and bases, to define acidity and explain how the pH scale relates to the acidity of a substance, to distinguish between strong and weak acids in relationship to the acid ionization constant (Ka), and to discuss the purpose of a pH titration curve and define the half-equivalence point and equivalence point. In so doing, we will perform pH analysis utilizing pH indicator strips, perform a titration of a weak acid against a strong base, construct an accurate titration curve using experimental results, and determine Ka for an unknown weak acid utilizing the data collected during the experiment.

Results

Experimental data (these can also be organized in a table or graph):

Calculations:

Experiment 1

Data Table 1: Determination of Equivalence Point

	Trial 1	Trial 2
Volume of Unknown Weak Acid	4 ml	4 ml
Total Number of Drops Required to Reach Equivalence Point	110	110
Average Number of Drops	110

Data Table 2: Titration Curve Values

Drops NaOH Added	pH Value Trial 1	pH Value Trial 2	pH Value (Average)
Half-Equivalent Point	55	55	55
Equivalent Point	110	110	110
0	4	4	4
10	6	6	6
20	6	6	6
30	6	6	6
40	6	6	6
50	6	6	6
60	7	7	7
70	7	7	7
80	8	8	8
90	8	8	8
100	10	10	10
110	10	10	10
120	10	10	10

Panel 1: Equivalent Point Number of Drops

46 Drops of NaOH

Panel 2: Half-Equivalent Point Number of Drops

93 Drops of NaOH

Data Table 3: Determination of Unknown

pKa of Unknown Weak Acid:	6.0
Ka of Unknown Weak Acid:	10-6
Unknown Weak Acid Identity:	Carbonic acid (H2CO3
% Error pKa:	5.81%
% Error Ka:	132.56%

pH indicator strips work by changing color in the presence of solutions with varied pH values. Thinking about your procedure steps and results in Part 1, why do you think the pH of the unknown weak acid was not determined with pH indicator strips until Part 2?

Discuss possible causes of error in the experimental procedure. Why do you think there was a percent of error in the pKa and Ka values of the unknown weak acid, in comparison to the values presented in Table 2?

Do you think using a pH meter instead of pH indicator strips would have created a larger or smaller percent error? Explain your answer.

5. Why was phenolphthalein a good indicator to use for determining the equivalence point between the unknown weak acid and strong base?
 

12 10 8 6 et 4 2 0 0 pH vs Drop of NaOH curve 20 40 60 80 Drops of NaOH 100 120 140