Vinegar Titration

Titration Analysis of Vinegar

Student: Araik Movessian
Grade: 12
Course: SCH4U
Teacher: Tijana Knezovic

Purpose and Introduction:

In this experiment the question of “what is the molar concentration of acetic acid in a sample of vinegar?” was answered via titration using a standard solution of sodium hydroxide, NaOH(aq).
In this investigation, students are to act as quality control chemists. Their purpose is to test the acetic acid concentration of the vinegar to discover whether it has been diluted. In this theoretical report, the manufacturer claims on the label that the vinegar contains 5% (0.87 mol/L) acetic acid. Thus, the concentration of acetic acid in the vinegar sample should be the same.

Materials

* Lab apron * Eye protection * NaOH(aq) * Vinegar * Phenolphthalein * Distilled water * Two 100mL beakers * 250mL beaker * 100mL volumetric flask with stopper * 50mL buret * 10mL volumetric pipet * Pipet pump * Retort stand * Buret clamp * Funnel * Erlenmeyer flask

Procedure

1. Obtain about 30mL of vinegar in a clean, dry 100mL beaker. 2. Pipet one 10.00mL portion into a clean 100mL volumetric flask and dilute to the mark. 3. Stopper and invert several times to mix thoroughly. 4. Obtain about 70mL of NaOH(aq) in a clean, dry, labeled 100mL beaker. 5. Set up the buret with NaOH(aq), following the accepted procedure for rinsing and clearing the air bubble. 6. Pipet a 10.00mL sample of diluted vinegar into a clean Erlenmeyer flask. 7. Add 1 or 2 drops of phenolphthalein indicator. 8. Record the initial buret reading to the nearest 0.1mL 9. Titrate the sample with NaOH(aq)until a single drop produces a permanent change from colourless to faint pink. 10. Record the final buret reading to the nearest 0.1mL. 11. Repeat steps 6 to 10 until three consistent results are obtained.

Results

Trial | 1 | 2 | 3 | Final Buret Reading(mL) | 13.2 | 27.6 | 40/4 | Initial Buret Reading(mL) | 0 | 13.2 | 14.4 | Volume of NaOH added(mL) | 13.2 | 14.4 | 12.8 | Average NaOH(mL) | 13.6 |
Table 1: The recorded data after three (3) trials of titration.

Figure 1: The solution on the left is a sample of the diluted vinegar before the addition of NaOH(aq). The solution on the right is a sample of the diluted vinegar after titration has taken place.

Conclusion

In conclusion, a sample of vinegar was analyzed via titration with a standard 0.0653 mol/L NaOH solution. The vinegar’s molar concentration was determined to be _________ mol/L. In comparison to the manufacturer’s data,