Question

Which metal is preferred for collecting hydrogen from :

(a) cold water ?

(b) hot water ?

(c) steam ?

Write balanced equation for each case.

Answer 1

(a) Cold water:

Sodium metal wrapped in small piece of wire gauze or Sodium amalgamated with mercury is used. This prevents sodium from darting about.
2Na + 2H₂O → 2NaOH + H₂ ↑

(b) Hot water:

Zn or Mg can be used.
Mg + H₂O → MgO + H₂ ↑
(boiling water)

(C) Steam:

Iron reacts with the steam and the reaction is reversible. Iron reacts with steam when it is red hot as hydrogen is blown out of contact with iron by the force of current of the steam.
3 Fe(steam) + 4H₂O → Fe₃O₄ + 4H₂