Turmeric, a natural compound, is added to mustard for flavor and color. It changes color from yellow — Acid-Base Titration Chemistry Question

This is a titration experiment. Yellow mustard must be between 2.6 – 3.5% acetic acid by law (See: Current CFR 21 for 2005 [ http://www.gpoaccess.gov/cfr/index.html ]http://www.gpoaccess.gov/cfr/index.html). Yellow mustard contains turmeric, here used as an indicator for this experiment.

The calculations would be: 1. moles base used (V x M) = moles acid present 2. moles acid present x molar mass acetic acid = mass acetic acid 3. Percentage of acetic acid in mustard = mass acetic acid present / mass mustard used
Sample Calculation: 0.50 g mustard weighed, titrated with a volume of 0.5 mL NaOH
moles OH^- = 0.0005 L x 0.5M = 0.00025 mol OH^- = 0.00025 mol H⁺ from HC₂H₃O₂ in mustard
mass HC₂H₃O₂ = 0.00025 mol x 60 g/mol = 0.015 g HC₂H₃O₂
finally, % acetic acid in mustard = 0.015 g /.50 g x100 = approx. 3.0%

The percentage of acetic acid in your sample of mustard = ___3.0%__________________

Excellent work: Student was able to complete two or more trials and average their results, using a minimum amount of both mustard and NaOH for each titration. Results were clearly shown and observations, i.e. color changes and endpoint were clearly noted. Student thought to make dilute aqueous solutions with each of the samples of mustard in order to completely dissolve the mustard and be able to more clearly note a uniform and lasting color change
Average work: Student only completed one trial. Evidence of a titration was performed. Measurements between trials were fairly consistent.
Below average work: Student was not able to conclude that this was a titration experiment, or did so, but did not perform the titration correctly to obtain a mass/volume of NaOH added. Only one trial was performed. Measurements were inaccurate or inconsistent between trials.