Exp3-molar_mass_procedure - Experiment Molar Mass of an...

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Web-in-sight : Nobel Prize winners: http://nobelprizes.com/nobel/chemistry/1986b.html Molar Mass of an Unknown Vapor Introduction Chem-Connections In lecture you’ll soon be learning about the properties of gases. The gas phase is the simplest form of matter, so it was a major focus of study for early chemists. Today gas phase chemistry still predominates in physical chemistry laboratories. Often, gases are handled in stainless steel vacuum chambers, injected through gas ports and focused into molecular beams. The beams can be sent to a variety of detection devices. Former UC Berkeley chemistry professor Yuan T. Lee established a new understanding of chemical reactions by using gas phase molecular beams, studies for which he shared the 1986 Nobel prize in chemistry. Famous chemists like Avogadro, Charles, Boyle, and Kelvin explored their theories of matter in the gas phase as well. In this investigation, you’ll use the properties of gases and your budding laboratory skills to measure a quantity you’ve heard a lot about, molecular mass. You’ll use a technique that was used by early chemists as they built up the database of weights and measures that led to the development of the relative atomic and molecular mass scale we use today. New Science At room temperature and atmospheric pressure all gases have similar properties. Say you had a 1 L bottle of a gas. If you heat it up, or squeeze the walls, the pressure inside will increase. If you cool the bottle or open it, the pressure decreases. With just these macroscopic observations, there is no way to tell what kind of gas is in the bottle. Gaseous CO 2 will behave pretty much like N 2 , or O 2 , or Ar or any other gas for that matter. This doesn’t happen with other phases of matter like solids and liquids. Some solids for instance, are compressible, others brittle others hard, depending on what they’re made of. The physical properties of gases however, don’t give any clues about what they’re made of. Gases can hide their identity like this because there is so much space between the particles in a gas. The individual particles hardly interact with each other at all, so the properties of the particles themselves don’t matter.
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Exp3-molar_mass_procedure - Experiment Molar Mass of an...

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