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Laboratory preparation of ethyne


Ethyne gas(Acetylene) is prepared in the laboratory by the action of water on calcium carbide.

CaC2 +  2H2O  ----------> C2H2 + Ca(OH)2   


Lumps of calcium carbide are placed on the layer of sand in conical flask fitted with a dropping funnel and delivery tube. Water is dropped from the dropping funnel whereby ethyne(acetylene)   is formed. It is passed through the acidified solution of CuSO4 for the purification.

Figure: Laboratory preparation of Ethyne(Acetylene) gas

Purification :

The  ethyne gas prepared by the above method contains impurities of H2S, PH3, NH3, AsH etc. due to the contaminations of calcium carbide. Therefore,  the gas is passed through acidified solution of  CuSO4 which remove the impurities as follows:

CuSO4  +  H2S  ----------> CuS  +H2SO4 

3CuSO4  +  2PH3 ----------> Cu3P2   +  3H2SO4 

2NH3  +  H2SO4 ---------->  (NH4)2SO4  

                                            3CuSO4  +  AsH3  +  3H2O ---------->  3 Cu  +  H3AsO3 + 3H2SO4                                                     

The pure gas is then collected by downward displacement of water.


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Nirdesh Pokharel asked 11 months ago

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Mousham khatiwada answered 8 months ago