What is titration?
Titration is the addition of one solution of a known concentration (the titrant) to a known volume of another solution of unknown concentration (the analyte) until one has just reacted completely with the other.
Titration is used in many types of food analysis as well as in chemistry labs.
Here's an example of how to calculate the percent of acetic acid in a sample of vinegar.
A 50.0 mL sample of vinegar was diluted to 250 mL. Titration of 20.0 mL of this solution required 28.0 mL of 0.100 mol/L NaOH. What was the mass percent of acetic acid in the vinegar? Assume that the vinegar has the same density as water.
Step 1. Calculate the moles of NaOH.
Moles of NaOH = 0.0280 L NaOH ×
Step 2. Write the balanced chemical reaction for the reaction
CH₃COOH + NaOH → CH₃COONa + H₂O
Step 3. Calculate the moles of CH₃COOH.
Moles of acetic acid = 0.002 80 mol NaOH ×
Step 4. Calculate the molarity of the diluted vinegar.
Step 5. Calculate the molarity of the original vinegar.
Step 6. Calculate the mass of CH₃COOH in the vinegar.
Mass of CH₃COOH = 0.0500 L vinegar ×
Step 7. Calculate the mass percent of acetic acid.
Mass percent =
The vinegar contains 4.20 % acetic acid.