What would a chemistry lab be without glassware? Common types of glassware include beakers, flasks, pipettes, and test tubes. Each of these containers has its own unique form and purpose.
Beakers are the workhorse glassware of any chemistry lab. They come in a variety of sizes and are used for measuring volumes of liquid. Beakers aren’t particularly precise. Some aren’t even marked with volume measurements. A typical beaker is accurate within about 10 percent. In other words, a 250-ml beaker will hold 250-ml +/- 25 ml of liquid. A liter beaker will be accurate to within about 100 ml of liquid.
The flat bottom of a beaker makes it easy to place on flat surfaces such as a lab bench or a hot plate. The spout makes it easy to pour liquids into other containers. Finally, the wide opening makes it easy to add materials to the beaker. For this reason, beakers are often used for mixing and transferring liquids.
There are multiple types of flasks. One of the most common in a chemistry lab is an Erlenmeyer flask. This type of flask has a narrow neck and a flat bottom. It’s good for swirling, storing, and heating liquids. For some situations, either a beaker or an Erlenmeyer flask is a good choice, but if you need to seal a container, it’s much easier to put a stopper in an Erlenmeyer or cover it with parafilm than it is to cover a beaker.
Erlenmeyer flasks come in multiple sizes. As with beakers, these flasks may or may not have volume marked, and they are accurate to within about 10 percent.
Test tubes are good for collecting and holding small samples. They aren’t typically used for measuring precise volumes. Test tubes are relatively inexpensive compared with other types of glassware. Those meant to be heated directly with a flame are sometimes made from borosilicate glass, but others are made from less sturdy glass and sometimes plastic.
Test tubes don’t usually have volume markings. They are sold according to their size and may have either smooth openings or lips.
Pipettes are used to deliver small volumes of liquids reliably and repeatedly. There are different types of pipettes. Unmarked pipettes deliver liquids drop-wise and may not have volume markings. Other pipettes are used to measure and deliver precise volumes. Micropipettes, for example, can deliver liquids with microliter accuracy.
Most pipettes are made of glass, while others are made of plastic. This type of glassware isn’t intended to be exposed to flames or extreme temperatures. Pipettes can be deformed by heat and lose their measurement accuracy under extreme temperatures.
Florence Flasks or Boiling Flasks
A Florence flask or boiling flask is a thick-walled, rounded flask with a narrow neck. It’s almost always made of borosilicate glass so that it can withstand heating under a direct flame. The neck of the glass allows a clamp so that the glassware can be held securely. This type of flask may measure a precise volume, but often no measurement is listed. Both 500-ml and liter sizes are common.
Volumetric flasks are used to prepare solutions. Each one features a narrow neck with a marking, usually for a single precise volume. Because temperature changes cause materials, including glass, to expand or shrink, volumetric flasks aren’t meant for heating. These flasks can be stoppered or sealed so that evaporation won’t change the concentration of a stored solution.