Glassware

When you check in to a laboratory drawer at the start of the semester, you will familiarize yourself with the glassware and equipment stocked for common use.¹ It is important to note that everything in your drawer should be returned clean at the end of each lab meeting. Anything that is provided on top of your lab bench should be left there at the end of each lab meeting. This includes specialty equipment (such as calorimeters) and volumetric glassware (such as pipets, volumetric flasks, and burets).² 

Volumetric glassware is a special type of glassware that is calibrated to contain or deliver a particular volume. In some cases, such as volumetric flasks and volumetric pipets, there is only a single calibration line. This means that the glassware is designed to contain or deliver a single precise volume. In other cases, such as burets or graduated pipets, there are many calibration marks. In these cases, it is important to always record a starting volume and a final volume for each measurement. 

You may also note the abbreviations TC or TD on glassware.³ TC stands for "to contain" meaning that the glassware is designed to hold a particular calibrated volume. A common example of this is a volumetric flask, which we use to make and dilute solutions. TD stands for "to deliver" meaning that the glassware is designed to dispense a particular calibrated volume. A common example of this is a volumetric pipet. 

Another important observation to note is any number that includes a % or +/- sign. This can give you an idea about how the glassware is meant to be used. For example, many beakers will only be accurate within 5% of the printed markings. They are not calibrated; rather, they are stamped in mass production. They should not be used when specific measurements are required. Conversely, a +/- notation will help you determine how many significant figures to record in your measurements. For example, a measurement from a 10 mL volumetric pipet that includes a notation of +/- 0.02 should be recorded as 10.00 mL.

How to clean laboratory glassware:

• Clean glassware at the sinks located at the back of each bench. Be aware of your surroundings, and do not leave glassware on the counter edge where it may roll off and break.

• Use a small amount of glassware soap (in the opaque cylindrical bottles) and tap water to wash your glassware.

• Scrub the inside and outside of your glassware with the provided brushes. Rinse and return the brushes to the bin when done.

• Rinse your glassware with tap water to remove suds. The more soap you use, the longer this will take!

• Do a final rinse of your glassware with deionized water, using your squirt bottle to reach all surfaces. This will prevent deposits of minerals from the tap water and ensure a clean surface. If you need to refill the deionized water bottle from your bench, refill from the spigot on the carboy at your sink.

• You don't need to dry your glassware when you put it away for the week. It will dry in your drawer without water spots if you follow the procedures above. If desired, you can lay it on a paper towel in your drawer.

References

1. Professor Dave Explains. "Common Scientific Glassware and the Undergraduate Chemistry Laboratory"  https://www.youtube.com/watch?v=RwBUgVDeRqw (Accessed July 24, 2024)

2. Compound Interest. "A Visual Guide to Laboratory Glassware" https://www.compoundchem.com/2015/03/17/glassware/ (Accessed July 24, 2024)

3. Globe Scientific. "What Are TD (To Deliver) and TC (To Contain), and How Do They Differ?" https://www.globescientific.com/laboratory-glassware-what-are-td-to-deliver-and-tc-to-contain-and-how-do-they-differ (Accessed July 24, 2024)