Concentration Using Titration

Determining the percent Concentration of a given Solution using Titration
Morphy Kuffour
Mrs. Langlis, AP Chemistry C-D
9/24/2017
Purpose:
Determining the precise concentration of vinegar through titration using a standard solution of Potassium Hydroxide (KOH) (aq)
Background:
Vinegar is a solution of acetic acid (CH3COOH) in water. The concentration of acetic acid in
Vinegar is written as a Molarity (mol/L). In this experiment, titration is used to determine the concentration of acetic acid in vinegar. Titration is an experimental technique for determining the concentration of a solution by reaction with something else. To perform a titration, a carefully measure amount of one reactant is added to an Erlenmeyer flask. An indicator is added
that will signal the endpoint of the titration by a visible color change. Then the other reactant is added slowly to the flask using a burette. When the indicator changes color, the reaction is complete and the volume of the is measured.
Materials & Equipment:
2.00 M KOH solution
Unknown M Vinegar
Potassium hydrogen phthalate C8H5KO4 (KHP)
Phenolphthalein (C20H14O4) - Indicator
125 mL Erlenmeyer flask
100 mL Burette
10.0 mL graduated cylinder
Weighing dish
Ring Stand
Clamp
Burette clamp
Deionized water squirt bottle
Deionized water
150-mL beaker
Balance
Pipette
Procedure:
Preparing the base burette:
First prepare 100.0 mL of 2.00 M solution in a volumetric flask.
1. Clean the interior of burette with deionized water.
2. After rinsing the burette add a little of KOH solution to the burette. Coat the inside of the burette with base.
3. Fill the burette with the 2.00 M KOH solution Record the initial burette reading at the meniscus.
Preparing the acid:
4. Rinse a 125-ml Erlenmeyer flask with deionized water. It is important that your glassware be scrupulously clean!
5.
Using a clean plastic weighing dish, obtain between 1.50 g of potassium hydrogen phthalate ( C8H5KO4) to a 125 Erlenmeyer flask and add about 50 mL of water. Swirl the flask to dissolve the KHP. Record the exact mass of KHP that you use.
6. Transfer all of the KHP to a very clean Erlenmeyer flask along with approximately 50 ml of deionized water. Squirt some
deionized water into the weighing dish to make sure all of the KHP is transferred into the flask.
Swirl the flask.
7. Add two of phenolphthalein indicator to the flask and swirl to mix.
Safety:
Goggles must worn including Lab coats and gloves can be worn if need be or when it’s appropriate. KOH is corrosive. If KOH solution splashes into your eyes or comes contact with skin, use the eyewash or flush the affected area with water.

Waste Disposal:
All solutions can be flushed down the sink with plenty of water.

Data and Calculations:
Table 1: Titration of KOH and KHP
Run Initial (mL) Final (mL) Equivalence Point (mL)
Rough 3.0 4.9 4.6
1 4.9 9.0 4.1
2 9.0 12.0 4
3 12.0 16.1 4.1
Average value for Equivalence point (mL) 4.2

Table 2: Vinegar Titration: 10.00 ml vinegar used for each titration
Run Initial (mL) Final (mL) Equivalence Point (mL)
Rough .2 5.4 5.2
1 5.4 10.7 5.3
2 20.4 25.5 5.1
3 25.5 30.7 5.2
Average value for Equivalence point (mL) 5.2
Conclusion:
In this experiment, an unknown concentration of unknown weak acid (acetic acid) was analyzed. We mad three trials, and the average molarity of the vinegar was determined to be 0.868 M. I found the percentage of the acetic acid, HC2H3O2(aq), in the vinegar to be
5.18%.