while manufacturing methane in laboratory why methane is collected by the downward displacement of water
Answers
Answered by
2
Laboratory Method
(A) Principle : In the laboratory,methane is prepared by heating a mixture of anhydrous sodium acetate and soda lime (NaOH + CaO)
CH3COONa + NaOH(CaO) --------> CH4 + Na2CO3
Sodium acetate Soda lime Methane
(B) Procedure : Anhydrous sodium acetate and soda lime are taken in the ratio 1:3 by weight and are mixed immediately.The intimate mixture of sodium acetate and soda lime thus prepared is taken in a dry hard glass test tube fitted with a cork through which a delivery tube passes.The hard glass test tube is now heated strongly when methane is evolved.The first part of the evolved gas is allowed to escape to remove the air inside the test tube.Methane thus produced is collected in a gas jar by the downward displacement of water
(C) Purification : Methane thus prepared contains traces of ethylene,acetylene,hydrogen and moisture as impurities.
(I)Acetylene is removed by passing the impure gas through ammoniacal cuprous chloride solution
C2H2 + CuCl2 ----NH3-----------> C2Cu2 + 2HCl
(II)Ethylene and moisture are removed by passing the gas through fuming sulphuric acid
C2H4 + H.HSO4-------------->C2H5HSO4
Ethyl hydrogen sulphate
(III)The gas is then mixed with excess of oxygen and the gas is passed over palladium heated at 100°C.H22 is removed by absorbing it in alkaline pyrogallate solution.The gas is then passed through conc.H2SO4 to remove water produced by the action of H2 and O2 and then collected over mercury present in methane is converted to water.
[Soda lime is used instead of NaOH alone in the preparation of methane from sodium acetate.This is because of the fact that,soda lime is cheap,less hygroscopic,does not fuse and attack so readily as caustic soda]
Preparation of Methane by the Action of Water on Aluminium Carbide
Methane can be prepared by the action of water or dilute acids on aluminium carbide at room temperature.
Al4C3 + 12H2O --------->3CH4 + 4Al(OH)3
Al4C3 + 12HCl --------->3CH4 + 4Al(Cl)3
Lumps of aluminium carbide are taken in a conical flask fitted with a drooping funnel and a delivery tube.Some dilute hydrochloric acid is taken in the drooping funnel which is dropped on aluminium carbide when methane is evolved.The evolved methane is collected in the gas jar by the downward displacement of water
(A) Principle : In the laboratory,methane is prepared by heating a mixture of anhydrous sodium acetate and soda lime (NaOH + CaO)
CH3COONa + NaOH(CaO) --------> CH4 + Na2CO3
Sodium acetate Soda lime Methane
(B) Procedure : Anhydrous sodium acetate and soda lime are taken in the ratio 1:3 by weight and are mixed immediately.The intimate mixture of sodium acetate and soda lime thus prepared is taken in a dry hard glass test tube fitted with a cork through which a delivery tube passes.The hard glass test tube is now heated strongly when methane is evolved.The first part of the evolved gas is allowed to escape to remove the air inside the test tube.Methane thus produced is collected in a gas jar by the downward displacement of water
(C) Purification : Methane thus prepared contains traces of ethylene,acetylene,hydrogen and moisture as impurities.
(I)Acetylene is removed by passing the impure gas through ammoniacal cuprous chloride solution
C2H2 + CuCl2 ----NH3-----------> C2Cu2 + 2HCl
(II)Ethylene and moisture are removed by passing the gas through fuming sulphuric acid
C2H4 + H.HSO4-------------->C2H5HSO4
Ethyl hydrogen sulphate
(III)The gas is then mixed with excess of oxygen and the gas is passed over palladium heated at 100°C.H22 is removed by absorbing it in alkaline pyrogallate solution.The gas is then passed through conc.H2SO4 to remove water produced by the action of H2 and O2 and then collected over mercury present in methane is converted to water.
[Soda lime is used instead of NaOH alone in the preparation of methane from sodium acetate.This is because of the fact that,soda lime is cheap,less hygroscopic,does not fuse and attack so readily as caustic soda]
Preparation of Methane by the Action of Water on Aluminium Carbide
Methane can be prepared by the action of water or dilute acids on aluminium carbide at room temperature.
Al4C3 + 12H2O --------->3CH4 + 4Al(OH)3
Al4C3 + 12HCl --------->3CH4 + 4Al(Cl)3
Lumps of aluminium carbide are taken in a conical flask fitted with a drooping funnel and a delivery tube.Some dilute hydrochloric acid is taken in the drooping funnel which is dropped on aluminium carbide when methane is evolved.The evolved methane is collected in the gas jar by the downward displacement of water
Similar questions