In 1787, Jacques Charles discovered that a gas expanded or contracted about 1/273rd for every degree Celsius rise/fall. Where did he keep that gas so that he could determine both temperature and the expansion/contraction of that gas to 1/273rd?
Asker: John, age 82
Answer
Hi Joannes,
Better late than never for an answer, isn’t it?
Charles probably took his measurements with a so-called gas burette. Click on the link on the left to see an image of such a setup.
There is gas in the Erlenmeyer flask on the left, and the Erlenmeyer flask is connected to the burette – the vertical tube in the center of the tripod – which is precisely graduated in milliliters. Its bottom is filled with water, and at the start of the experiment the glass ball on the right (also half filled with water) is raised so that the liquid level is at the top of the burette.
Now if you heat the unit (Charles lit the fireplace in the room, for example) the gas inside will expand, pushing the water in the burette down. By adjusting the height of the ball on the right you can ensure that the level in the ball and the burette remains exactly the same, so that the pressure in the device also remains exactly the same as the pressure outside.
In this way you can read gas volumes directly, without having to calculate.
All you need is enough patience and a good thermometer.
I dare not put my hand in the fact that Charles’s machine looked exactly like this, but at least it must have looked very much like it.
Kind regards,
Christophe Vande Velde
Answered by
Prof. dr. Dr Christophe Vande Velde
Thermal Analysis, Calorimetry, X-ray Crystallography, Organic Chemistry
University of Antwerp
Prinsstraat 13 2000 Antwerp
http://www.uantwerpen.be
Prinsstraat 13 2000 Antwerp
http://www.uantwerpen.be
.