DOWNLOAD HSEB NOTES ON THERMAL PROPERTIES AND IDEAL GASES | CHEMISTRY
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Boyle's Law : Pressure and volume of an enclosed sample of gas
If you have ever tried to force in the plunger of a syringe or a bicycle pump while sealing the opening with a finger you will know that there is some sort of inverse relationship between the force you apply and how far in you can push it. Greater and greater forces are needed to push the plunger further and further in. In other words, the smaller you make the volume of the enclosed air, the
bigger the pressure of that enclosed air. Scientific progress is closely related to technological development : they feed and support each other. No real progress could be made in the study of gases until the 17th century when the first efective vacuum pumps were developed. An Englishman named Robert Boyle designed some excellent vacuum pumps which allowed him to take very accurate measurements over a good range of pressures and volumes. He discovered the startlingly simple fact that the pressure and volume are not just vaguely inversely related, but are exactly inversely proportional.
Definition: Boyle's Law:
The pressure of a fixed quantity of gas is inversely proportional to the volume it occupies so long as the temperature remains constant. The standard modern laboratory version of his apparatus consists of a vertical glass tube sealed at the top end, with the other end filled up to a certain point with oil. This end is attached to an oil reservoir, which in turn has a layer of air above it (which the oil keeps separate from the trapped air.) The air trapped in the tube by oil is then subjected to various pressures (usually a bicycle pump is used to pump in air through a non-return valve) which are registered by a Bourdon gauge. As the air pressure above the oil inside the reservoir is increased, the pressure of the oil on the trapped air increases. The change in volume of the air in the tube can be read of on a scale next to it. (NOTE TO SELF: Include a diagram here!!!)
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Chemistry