Percentage of acetic acid in vinegar lab answers

Final Report

Exercise 1

CHEM 182 DL1 Titrat ion for Acetic Acid in Vinegar

20% error

1. T he manufacturer of the vinegar used in the experiment stated that the vinegar contained 5.0% acetic acid. What is the percent error between your result and the manufacturer statement? Show your work.

We use white vinegar in this experiment so that we can see the color change. In addition, balsamic vinegar contains a few different elements.

2. What challenges would you encounter with the t itration if you had used apple cider vinegar or balsamic vinegar as the analyte instead of white vinegar?

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You want to fill the tip to release any air bubbles and so you can have it be one drop at a time so you don’t let too much out at a time.

3. If the t ip of the syringe, "T he T itrator", was not f illed with NaOH before the init ial volume reading was recorded, would the concentration of acetic acid in vinegar of that trial be greater than or less than the actual concentration? Please explain your answer.

This would most likely mess with our calculations and make our percentage wrong.

4. How would your experimentally determined vinegar concentration have dif f ered if you had over-t itrated (added drops of NaOH to the analyte beyond the stoichiometric equivalence point)?

Macid = 1.6 M

1.6 M * 60g = 96g CH3COOH

96g/7.0mL = 13.71

Mass percent = 13.7%

5. If a 7.0 mL sample of vinegar was t itrated to the stoichiometric equivalence point with 7.5 mL of 1.5M NaOH, what is the mass percent of CH COOH in the vinegar sample? Show your work.

3

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Data Table 1: NaOH Titration Volume

It is important to do multiple trials of titration because you are dealing with such a precise amount such as a drop at a time. You could have messed up on one of your trials without realizing it. It is best to do more than one trial and take the average.

6. Why is it important to do multiple trials of a t itration, instead of only one trial?

Initial NaOH Volume (mL)

Trial 1

Trial 2

Trial 3

Final NaOH Volume (mL)

Trial 1

Trial 2

Trial 3

Average Volume of NaOH Used (mL):

Total Volume of NaOH Used (mL)

Trial 1

Trial 2

Trial 3

10 mL

10 mL

10 mL

3.6 mL

3.2 mL

3.0 mL

6.4 mL

6.8 mL

7.0 mL

6.73 mL

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Data Table 2: Concentration of CH3COOH in Vinegar

Average Volume of NaOH Used (mL)

Concentration CH COOH in vinegar (mol/L)

Average Volume of NaOH Used (mL) % CH COOH in vinegar

3

6.73 mL 0.673 mol/L

3

6.73 mL 4.0%