What is the Acidity of Vinegar? - Exploration

Laboratory

Background

We are tasked with determining two aspects of

vinegar. The first is determining how the acetic

acid (CH₃COOH) concentrations compare between

different brands of vinegar. In other words, can I

swap one brand of white-distilled vinegar for a

different brand of white-distilled vinegar and

expect to see the same results? The second

question is whether the labels are correct on

bottles of vinegar. In other words, are the

manufacturers truthful with their labeling?

Vinegars are labeled with the percent of their

acidity. Acetic acid is the only acid in white-

distilled vinegars. Percent acidity is a weight-to-

weight percent, meaning that if a vinegar is

labeled as 5% acidity, then it has 5 grams of

acetic acid for every 100 grams of solution.

Experiment

Acetic acid reacts with sodium hydroxide to make water and sodium acetate. It is

an ideal candidate for using the titration techniques we practiced last week.

This is a two-week lab where you are tasked with answering the two questions

above. In the first week of the laboratory, you will plan your experiments and

start to carry them out. In the second week of the laboratory, you will finish

carrying out data collection and analyzing the data to answer the two questions

posed above.

Available Materials

0.100 M NaOH; burets; 100 mL volumetric flasks; 5, 10, and 25 mL volumetric

pipets; phenolphthalein; three different vinegars.

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Figure 7.1: ”Vinegar” by HomeSpot HQ

is licensed under CC BY 2.0.