Chemistry · Ch 6 — Gaseous State
Introduction
Introduction
Of the three states of matter, the gaseous state is the simplest to describe mathematically -- and, in the form of the air you breathe every few seconds, the one you depend on most continuously.
What this unit sets out to do. By the end of it you should be able to:
- state the laws that govern an ideal gas, and recognise them at work in everyday situations;
- derive the ideal gas equation and use it in calculations;
- state how real gases deviate from ideal behaviour, and derive the van der Waals equation that corrects for it;
- define Graham's law of diffusion and the compressibility factor;
- explain critical phenomena, and derive the critical constants in terms of the van der Waals constants;
- explain Andrews's isotherms of carbon dioxide;
- describe the Joule-Thomson effect and how gases are liquefied.
Note
James Clerk Maxwell -- quoted at the start of this unit for his insight that a gas's macroscopic properties come from the rapid, ceaseless motion of its molecules -- is the physicist whose statistical treatment of that motion underlies almost everything in this unit, from the ideal gas equation to why real gases deviate from it.