The manufacturer of the vinegar used in this experiment

Titration for Acetic Acid in Vinegar

Hands-On Labs, Inc. Version 42-0208-00-02

Lab Report Assistant

This document is not meant to be a substitute for a formal laboratory report. The Lab Report Assistant is simply a summary of the experiment’s questions, diagrams if needed, and data tables that should be addressed in a formal lab report. The intent is to facilitate students’ writing of lab reports by providing this information in an editable file which can be sent to an instructor.

Exercise 1: Determining the Concentration of Acetic Acid

Data Table 1. NaOH Titration Volume.

Initial NaOH Volume (mL)

Final NaOH Volume (mL)

Total volume of NaOH used (mL)

Trial 1

9

2

7

Trial 2

9

0.5

8.5

Trial 3

9

3

6

Average Volume of NaOH Used (mL) :

Data Table 2. Concentration of CH3COOH in Vinegar.

Average volume of NaOH used (mL)

Concentration CH3COOH in vinegar (mol/L)

% CH3COOH in vinegar

7.16

0.716

6

Concentration CH3COOH in Vinegar = 0.00716L X 0.5/L X (1Mol CH3COOH/ 1 Mol NaOH) X 1/ 0.005L

Concentration of CH3COOH in Vinegar = 0.716Mol

Questions

A. The manufacturer of the vinegar used in the experiment stated that the vinegar contained 5.0% acetic acid. What is the percent error between your result and the manufacturer’s statement?

% Error = (6 – 5 / 5 ) x 100

= 20%

B. What challenges would you encounter with the titration if you had used apple cider vinegar or balsamic vinegar as the analyte instead of white vinegar? The white vinegar is made up of pure vinegar so the results will be more accurate than the apple cider vinegar or balsamic vinegar, the later has other “impurities” in them. The apple and balsamic has other properties which will interfere with the titration.

C. How would your results have differed if the tip of the titrator was not filled with NaOH before the initial volume reading was recorded? Explain your answer.

D. How would your results have differed if you had over-titrated (added drops of NaOH to the analyte beyond the stoichiometric equivalence point)?

E. If a 7.0 mL sample of vinegar was titrated to the stoichiometric equivalence point with 7.5 mL of 1.5M NaOH, what is the mass percent of CH3COOH in the vinegar sample?

F. Why is it important to do multiple trials of a titration, instead of only one trial?