Anthony Vitiello
Doctor Murphy
5/17/18
Chemistry (H)
The Investigation about Titration being used in Vinegar
Objective: To find out how much acetic acid is in vinegar
When the concentration of an acid is unknown, a titrant of the known concentration is used. The titrant is usually added, drop by drop, into the acid until it is completely
neutralized by the base. What this experiment will test is the concentration of the acid. What will be tested is common vinegar and apple cider vinegar, since both have a percent of acetic acid(5%) in both of them.
Materials:
1. 1 24 well microplate
2. 1% of acetic solution
3. Phenophthalein indicator
4. Apple cider vinegar
5. Common vinegar
6. 4 test tubes
7. burette
Procedure:
1. Place 10 drops of 1% acetic acid solution in well A1 of the 24 microplate. Add 1 drop of phenophthalein indicator to the same well.
2. Fill the burette with the 0.1M sodium hydroxide and return the burette ti the holder.
3. Carefully counting the drops, add the 0.1M sodium hydroxide solution to the acetic acid solution, drop by drop, until the phenophthalein turns a light pink color which persists for more than 30 seconds,. Record the number of drops.
4. Discard the solution in well A1 and rinse the well with distilled water. Rinse the toothpick of plastic stirrer and dry with a paper towel or filter paper.
5. Repeat steps 2 through 5 at least twice more. Average your results and record the value as standard titrant.
Sample Titration 1:
6. For the sample 1 titration, you will do the NaOH titration of white vinegar. Use a test tube for this reaction instead of the 24-well plate.
7. Repeat steps 2 through 5 above, substituting 10 drops of white vinegar for 10 drops of acetic acid. Repeat the procedure three times and average your results. This average is the sample titrant 1.
Sample titration 2:
8. For the sample 2 titration, you will do a NaOH titration of apple cider vinegar for apple cider vinegar. Use a test tube for this reaction instead of the 24-well plate.
9. Repeat steps 2 through 5 above, substituting 10 drops of apple cider vinegar for 10 drops of acetic acid. Repeat the procedure three times and average your results. This average is the sample titrant 2.
Calculations: sample titrant/standard titrant=% acetic acid in vinegar. Divide each sample titrant average by the standard titrant average.
1%acetic acid
Trial 1
Trial 2
Trial 3
# drops of 0.1M
NaOH
16
30
80
White vinegar
Trial 1
Trial 2
Trial 3
# drops of 0.1M
NaOH
120
108
90
Apple Cider Vinegar
Trial 1
Trial 2
Trial 3
# drops of 0.1M
NaOH
109
116
130
% acetic acid in white vinegar:2.52
% acetic acid in apple cider vinegar:2.82
In this experiment, my hypothesis was incorrect, as they should have been at least 5%.
Both of the vinegar had less than 3% of acetic acid, which isn’t what my hypothesis
stated.
