Notes
Data Collection
When collecting data, keep everything well organized and labeled. Think about
the experiments you will be performing. What data will need to be recorded? Set
up tables for yourself to keep the data organized.
We want to be able to quantify both the value and the repeatability of your
measurements (relative average deviation). You should have at least three trials
for each of the three vinegar samples.
Additional Considerations
Think back to last week’s titrations. We said that titrations should take between
10 and 50 mL of titrant. That means if we are using 0.100 M NaOH, that we can
deliver between 0.00100 moles and 0.00500 moles of NaOH to create a quality
titration. Therefore, the moles of acid in the analyte in the Erlenmeyer flask must
be completely reacted with somewhere between 0.00100 and 0.00500 moles of
NaOH.
Commercial vinegar samples contain roughly 5% by weight of acetic acid. If we
assume the solution has a density of 1.0 g/mL, then the approximate molarity of
acetic acid in vinegar is
Think about this when determining how much acetic acid solution to use. If you
have too many moles of acid, you can either use a smaller volume of the acid or
dilute the acid in a volumetric flask and then titrate the diluted acid.
Safety Considerations
Acids and bases can be harmful to both your skin and eyes.
Wear eye protection and wash hands regularly to avoid having harmful materials
come into contact with your eyes.
If you spill acids or bases on your skin, immediately wash thoroughly with soap
and water.
57