milestones

# Milestones - Avicenna(c 980 1037 Persian polymath the foremost physician and philosopher of his time He was also an astronomer chemist geologist

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1 Avicenna (c. 980 – 1037) Persian polymath; the foremost physician and philosopher of his time. He was also an astronomer, chemist, geologist, logician, paleontologist, mathematician, physicist, poet, psychologist, soldier, statesman, and teacher. He invented the refrigeration coil, which condenses aromatic vapors. This was a breakthrough in distillation technology and he made use of it in his steam distillation process to separate temperature sensitive material and produce essential oils. Development of the Kelvin Absolute Temperature Scale • William Thomson (later Lord Kelvin) was interested in Charles’s Law which states that when a gas is cooled by one degree Celsius, it’s volume drops by 1/273 – This would lead to zero volume at -273 ° C – How can matter exist without taking up space? • Thomson instead suggested that it was the energy of motion that decreased with temperature – At -273 ° C, the molecules cease motion and essentially not take up space – He called -273 ° C absolute zero because no further temperature reduction is possible. This later became known as 0 Kelvin. Sources: University of Glasgow and World of Scientific Discovery Lord Kelvin Liquefaction of Oxygen Liquid oxygen is the liquid form of element oxygen. In nowadays it is widely used in many fields. Liquefaction of substance that normally exists as gas dates back to the 18th century. The first successful attempt was made by a French mathematician Gaspard Monge, who liquefied sulfur dioxide in 1784. In the following decades, people succeeded in liquefy many gases, but none of them was able to liquefy oxygen gas. In the late 1840s, Irish physical chemist Thomas Andrews suggested that every gas has a precise temperature, which is the critical temperature. Above the temperature gas cannot be liquefied even under great pressure. Following Andrews idea, scientist came up with the idea of using ’cascade’ process to get low temperature. In this method, one liquefied gas is used to cool another gas with lower critical temperature, and so on. By using the cascade process, French physicist Louis Paul Cailletet liquefied three gases, oxygen, nitrogen and carbon monoxide. Now liquid oxygen is playing a significant role in both industry and research. Compare with oxygen gas, liquid oxygen is much easier to store and transport. Liquid oxygen is stored in hospitals for patients with breathing problems. It is also used as oxidizer in industry, such as producing ion and many other metals. Furthermore, liquid oxygen is used as oxidizer in spacecraft such as rockets. Without liquefaction of oxygen, one cannot provide enough oxygen with such limited space and cannot put rocket into use. Liquefaction of oxygen is an important event in the history. It was one of the human

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## This note was uploaded on 10/22/2011 for the course PHY 4550 taught by Professor Ihas during the Spring '08 term at University of Florida.

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Milestones - Avicenna(c 980 1037 Persian polymath the foremost physician and philosopher of his time He was also an astronomer chemist geologist

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