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Argon–argon (or 40 Ar/ 39 Ar) dating is a radiometric dating method invented to supersede potassium–argon (K/Ar) dating in accuracy. The older method required splitting samples into two for separate potassium and argon measurements, while the newer method requires only one rock fragment or mineral grain and uses a single measurement of argon isotopes.
Argon (18 Ar) has 26 known isotopes, from 29 Ar to 54 Ar, of which three are stable (36 Ar, 38 Ar, and 40 Ar). On the Earth, 40 Ar makes up 99.6% of natural argon. The longest-lived radioactive isotopes are 39 Ar with a half-life of 268 years, 42 Ar with a half-life of 32.9 years, and 37 Ar with a half-life of 35.04 days.
Ar is the reason the standard atomic weight of terrestrial argon is greater than that of the next element, potassium, a fact that was puzzling when argon was discovered. Mendeleev positioned the elements on his periodic table in order of atomic weight, but the inertness of argon suggested a placement before the reactive alkali metal .
The most efficient method of industrial oil degassing is vacuum processing, which removes air and water solved in the oil. [6] This can be achieved by: spraying of oil in large vacuum chambers; distributing the oil into a thin layer over special surfaces (spiral rings, Raschig rings etc) in vacuum chambers.
Kinetic diameter is a measure applied to atoms and molecules that expresses the likelihood that a molecule in a gas will collide with another molecule. It is an indication of the size of the molecule as a target.
The oil and the oil filter need to be periodically replaced; the process is called an oil change. While there is an entire industry surrounding regular oil changes and maintenance, an oil change is a relatively simple car maintenance operation that many car owners can do themselves.
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The Gas composition of any gas can be characterised by listing the pure substances it contains, and stating for each substance its proportion of the gas mixture's molecule count.Nitrogen N 2 78.084 Oxygen O 2 20.9476 Argon Ar 0.934 Carbon Dioxide CO 2 0.0314