Question

why are calcium, iron,aluminium, and sodium metals not used in labouratory preparation of hydrogen?

Answer 1

because they are metal and solid element not gas elements

Answer 2

$\LARGE{ \underline{\underline{ \pink{ \bf{Required \: answer:}}}}}$

The following metals not used in the lab preparation of hydrogen and why 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)