3/6/2013 5:32:00 PM
Part I
Trial 1
Trial 2
Trial 3
50
50
50
30
35
20
30
26
38
Initial volume of NaOH in the buret
Volume of HCI in the flask
Volume of NaHO remaining at the end
point
Part II
Trial 1
Trial 2
Trial 3
50
50
50
20
25
30
0.70
0.70
0.70
30
30
25
0.96 | 1.3 | 2.15
0.9 | 1.15 | 1.5 |
0.87 | 1.06 | 1.3
| 7.00 | 12.7
7.00 | 12.4
| 1.7 | 7.00
12.85 | 12.94 |
12.66 | 12.8 |
13 | 13.05 |
12.89 | 12.95 |
13.08
13
12.4 | 12.63 |
12.76 | 12.85 |
12.91
Initial volume of NaOH in the buret
Volume of HCI in the flask
pH when 0 mL of NaOH has been added
Volume of NaHO remaining at the end
point
pH of solution each time an increment of
5 ml of NaOH is added. 5 | 10 | 15 | 20
| 25
pH of solution each time an increment of
5 ml of NaOH is added.30 | 35 | 40 | 45
| 50
Complete the following calculations for each part of the lab, showing your work neatly,
labeling each calculation with a subtitle, and giving a brief written explanation of each
calculation.
1. Determine the volume of sodium hydroxide added to the flask from the buret.
2. Calculate the molarity of the Hydrochloric acid in the flask. You may refer to the
Titration demo at the beginning of the honors lesson, just above the Virtual Lab
to see sample calculations.
3. Describe the graph of pH values over the course of the reaction in Part II. Was
the change in pH consistent over the course of the reaction? Do your best to
explain the reason for the shape of the pH curve in your own words.
4. Why is it important to stir the solution in the flask as you add titrant from the
buret?
5. If a student did not remove all of the bubbles from inside the buret before reading
the initial volume and beginning the titration, will this cause the calculated
concentration of the hydrochloric acid determined from that trial to be higher or
lower than the actual concentration? Explain your answer in complete sentences.
6. Describe at least three possible sources of error in a titration experiment like this
and, for each, explain whether the error would result in a calculated molarity that
is too high or too low.