Question

what is the process invovled in the dewar method of separation of inter gases?

Answer 1

Step i: The mixture of noble gases is brought in contact with charcoal (Charcoal -1)kept in a Dewar's flask maintained at a temperature of 173K.It is allowed to remain for one hour, when argon, krypton and xenon gases get adsorbed while helium and neon remain unadsorbed and are pumped out of the bulb.

Step ii: The mixture of helium and neon is introduced into another bulb containing coconut charcoal (Charcoal - 2) maintained at a temperature of 93K.Only neon gets adsorbed leaving behind helium which is pumped out. This charcoal is warmed to recover neon.

Step iii: The first charcoul with Argon, Krypton and Xenon adsorbed on it is brought in contact with another charcoal (Charcoal - 3) cooled to liquid air temperature (11K). Argon being a lighter gas diffuses into this charcoal (at 77K)and is recovered by warming separately.

Step iv: Krypton and Xenon which are still on the first charcoal (Charcoal -1)are separated by raising the temperature of the charcoal to 183X". At this temperature krypton cannot remain in the adsorbed state and it is collected. Xenon which remains on the first charcoal is released by warming and is collected separately. All these changes are shown schematically


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Answer 2

(There is some error in the question. The correct question can be read as: What is the process involved in Dewar's method of separation of inert gases?)

The process involved in Dewar's method of separation of inert gases is charcoal adsorption.

Explanation:

• The separation of a mixture of inert or noble gases can be carried out with the help of Dewar's method in which the charcoal adsorption process takes place.
• In this method, a double-walled flask is filled with activated charcoal.
• The mixture of gases is introduced into the flask with the help of a tube attached above the flask. The unadsorbed gases are also separated by it.
• The adsorption of gases depends upon temperature.
• Inert gases with low atomic mass are adsorbed at low temperatures.
• Charcoal adsorbs different gases at different temperatures. Therefore, they can be separated at different temperatures by this method.

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