Titration of Vinegar
Perform an acid-base titration to determine the concentration of acetic acid in vinegar. Add NaOH from the burette until the phenolphthalein indicator turns faint pink (end point).
Add NaOH solution drop by drop until the solution turns a faint pink color that persists for 30 seconds.
The Science Behind Titration
Titration is a technique to determine the concentration of an unknown solution:
- Vinegar contains acetic acid (CH₃COOH)
- NaOH is a strong base with known concentration
- Phenolphthalein is a pH indicator (colorless in acid, pink in base)
- Equivalence point occurs when moles acid = moles base
- End point (color change) should match equivalence point
CH₃COOH + NaOH → CH₃COONa + H₂O
This is an example of a neutralization reaction.
Macid × Vacid = Mbase × Vbase
Where:
Macid = Molarity of acetic acid
Vacid = Volume of vinegar (known)
Mbase = Molarity of NaOH (known)
Vbase = Volume of NaOH used (measured)
1. Measure known volume of vinegar into flask
2. Add 2-3 drops of phenolphthalein indicator
3. Fill burette with standardized NaOH solution
4. Add NaOH slowly while swirling flask
5. Stop at first permanent faint pink color
6. Record volume of NaOH used
7. Calculate acetic acid concentration
