Acid- Base Titration Lab

Topics: PH indicator, Titration, Phenolphthalein Pages: 3 (742 words) Published: October 23, 2013

Acid-Base Titration and Volumetric Analysis

The purpose of this experiment is to determine the [NaOH] of a solution by titrating it with standard HCl solution, to neutralize a known mass of an unknown acid using the NaOH solution as a standard, to determine the moles of NaOH required to neutralize the unknown acid, and to calculate the molecular mass of the unknown acid. Procedure:

Part A:
Standarized 0.10M HCl solution and unknown NaOH solution were poured into two beakers. The burets were then filled with the solution and put into the flask. Water was then added to the same flask. Then phenolphthalein indicator solution was added before we began titrating by adding more drops of the NaOH solution while swirling the flask until a pink color remained. The liquid levels were recorded on both burets. Part B:

Solid unknown acid was added to a flask with water and swirled until almost fully dissolved. Then phenolphthalein indicator was added. With standardized NaOH solution we titrated and recorded the initial and final volumes.

Data:
Acid-Base Titration

Initial Volumes
Final Volumes
Volume Used
Part A Acid
11.21mL
21.18mL
9.97mL
Part A Base
1.43mL
12.34mL
10.91mL
Part B Base
12.34mL (1st)
38.36mL (2nd)
50.00mL (1st)
50.00mL (2nd)
37.60mL (1st)
11.64mL (2nd) Total:49.30mL
Part B Mass of Acid
0.983g

Questions:
1. The molarity of the base NaOH is 0.091M.

2. The number of moles of NaOH that reacted with the unknown acid is 0.0045mol.

3. There are 0.0045mol of hydronium ion in 1 gram of the unknown acid because the mole to mole ratio of NaOH to the unknown acid is 1:1. So if there was 0.0045mol of NaOH, because of this ratio of 1:1, there will also be 0.0045mol of H3O+.

4. The molar mass of the unknown acid is 220.

1. When the end point is reached in an acid-base titration, the relationship between the concentrations of OH- and H3O+ are that they are equal. This...
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