silver metal cannot be used for the lab preparation of hydrogen gas,why?
Answers
Answer:
dilute HNO3 is not used for hydrogen preparation. To prepare hydrogen in the laboratory, metals like Na and K are not used because their reactions with mineral acids are too violent (although hydrogen is produced)
The following metals not used in the lab. preparation hydrogen and how are described below:
Calcium:
Calcium is not used in laboratory preparation of hydrogen as calcium has a very uncontrollable reaction with dilute H2SO4 or dilute HCl.
Iron:
Fe is not used becaused Fe needs to be heated due to which impurities like H2S,SO2 gases are produced.
Aluminium::
Due to its highly negative redox potential, Al should react readily with water producing hydrogen gas but practically Al is passivated by formation of highly adhering surface film of aluminium oxide when Al metal is oxidised and this interferes with the Al water reaction at the surface of metal.
Sodium:
Sodium is very reactive in nature and readily forms its hydroxide in the presence of air and moisture and can not be used to form hydrogen.
Jalaj Kumar Mahato (Nobilian)