JOVE-Common Glassware(1).pdf - Journal of Visualized Experiments www.jove.com Science Education Collection Common Lab Glassware and Uses URL

JOVE-Common Glassware(1).pdf - Journal of Visualized...

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Journal of Visualized ExperimentsCopyright © 2016 Page 1 of 3Science Education CollectionCommon Lab Glassware and UsesURL: OverviewSource: Laboratory of Dr. Neal Abrams — SUNY College of Environmental Science and ForestryGlassware is a regular appearance in the professional chemistry laboratory, because it has a relatively low cost, extreme durability, and specificlevels of precision. While some labware is being supplemented with plastic or even everyday kitchen materials, glass is still the standard materialby which laboratory work is done. While there are few rules about glassware, there are some best practices for use that set the groundwork forgood techniques in the lab.Glass is ubiquitous in the chemistry laboratory, but not all glass is the same. Standard consumer-grade glass is known as "soda-lime" or "float"glass. It is good for many applications, but cracks under rapid heating and cooling applications due to expansion/contraction. Borosilicate glassis used to solve this problem in the lab. Made with an introduction of small amounts of boron, borosilicate glass has a very low coefficient ofexpansion, which prevents internal stresses. The most common trade name for borosilicate glass is Pyrex, the same type of glass used in somekitchen bakeware.While borosilicate glass is thermally robust, the impurities found in borosilicate and standard glass lead to a limited temperature range andoptical quality. Fused silica, or quartz, is used in situations where glass needs to be heated above 450 °C or to be transparent to UV light. Fusedsilica is chemically-pure silicon dioxide with no impurities and a very high melting point above 1,600 °C. The easiest way to tell the differencebetween borosilicate glass and fused silica in the lab is to look down the long axis of a piece of glassware. A greenish color is indicative ofborosilicate impurities, whereas fused silica is optically clear and colorless.PrinciplesStandard laboratory glassware, like beakers and flasks, has a limited accuracy of measuring volume, typically ±5%. Volumetric glassware,however, is considered very accurate. This accuracy is known to the user through a few different pieces of information on the glassware. Forone, an etched line or volume marking is typically located on volumetric glassware to indicate a volume. The next piece of information is thetemperature at which the glassware is accurate, typically 20 °C. This is important because the density (and volume) of a liquid are dependent ontemperature. Thirdly, the notations "TD" or "TC" are used to indicate "to deliver" or "to contain", respectively. When a piece of glass is marked as"TD", it is calibrated to accurately deliver the stated volume, whereas glassware with the "TC" marking only contains a specified volume, but itmay not transfer to another vessel accurately.

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