Titration of Vinegar Lab!

Today in Chemistry class, we did a lab to figure out the Molar Concentration of Acetic Acid in   household vinegar.

1. For the lab we set up a buret on a lab-stand with a clamp.

2. We filled the buret with 0.50M NaOH, and filled an Erlenmeyer flask with 10mL of vinegar and put two drops of Phenolphthalein Indicator in it. 

3. Then we recorded the initial volume of the NaOH in the buret, and then added the NaOH to the vinegar and swirled the flask until the solution turned light pink.

4. We then recorded the final volume to find the total amount of NaOH added in the trial.

   * We did this more than once.

Trial                                                1                           2

Initial Volume                              7.8                         24.2

 (mL)

Final Volume                               24.2                      40.8

 (mL)

NaOH Added                               17.0                    17.2

(mL)

 5. Then we got the average volume of NaOH added.

       17.0 + 17.2 / 2 = 17.1 mL

6. We finally determined the concentration of Acetic Acid using the balanced equation from the reaction of NaOH and CH3COOH.

NaOH + CH3COOH = H2O + NaCH3COOH

0.50mol/L x 17.1mL x 1/1 = 8.6mmol

8.3mmol x 1/10 mL = 0.86M

The accepted value for the concentration of household vinegar is 0.85M.

% error = 0.86 – 0.85 / 0.85 x 100 = 1% error.

For a better understanding of what we did today in class, here is a video demonstrating our lab.