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You will use a 5.00 mL volumetric pipet to perform the dilution of the HCl unknown.
Watch the video below on the proper use of a volumetric pipet with a 3-way pipet bulb.
3-way pipet bulb
Add about 20 mL of distilled water to a 250.00 mL volumetric flask.
Safety: When diluting a solution of concentrated acid, it is important to start by pouring a small amount of water into the flask before adding acid to the container. Pouring the acid first and then adding water can result in a reaction energetic enough to cause the water to boil on contact. Pouring a small amount of water spreads out the energy release, although the mixture and the original concentrated sample still need to be handled with care.
250 mL volumetric flask being filled with
approximately 20 mL of distilled water
Rinse a clean 5.00 mL volumetric pipet with a small amount of the unknown concentrated HCl solution two times.
To rinse the pipet, draw up a small amount of solution, tilt to wet the sides, and then drain into a waste beaker.
You may notice some amount of solution remains in the pipet. This is normal and is accounted for in the calibration of the pipet.
If a drop remains at the tip of the pipet, make sure it ends up in your flask. Collect it by touching the side of the flask to the pipet tip.
Draw up the unknown concentrated HCl into the 5.00 mL volumetric pipet until the fluid level is a little past the line.
Drain the pipet slowly into a waste beaker until the bottom of the meniscus is on the line.
Dispense the 5.00 mL HCl into the 250.00 mL volumetric flask that already contains a little water. Fill the flask about half way with distilled water and swirl the acid/water mixture.
mixture of water and concentrated HCl unknown being swirled
Using a wash bottle, rinse the neck of the flask with distilled water.
Continue adding water until the meniscus level reaches just into the neck of the flask.
Stopper the flask and mix end over end several times.
Now add water more carefully. Using a plastic pipet, add distilled water until the meniscus exactly reaches the line on the flask without going over.
Mix thoroughly again, end over end, 20 or more times.
You have now made a dilute HCl solution which will be used for titration.
Volumetric flask with the HCl solution. Distilled water is added to fill the flask to the 250.00 mL volume mark.
250.00 mL volumetric flask filled so that the bottom of the meniscus is level with the 250.00 mL volume mark.
(Viewed with a meniscus reader).
Mixing contents in a volumetric flask.
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