Properties Of Hydrogen

The atomic form of hydrogen produced at the time of chemical reaction is known as nascent hydrogen. Nascent means newly born.

Zn + H₂SO₄ → ZnSO₄ + 2 H(nascent)
H + H → H₂

Physical properties

• Hydrogen is a colorless, tasteless and oodorlessgas.
• It is about insoluble in water.
• It is the lightest gas.
• It is neutral to litmus.
• It liquefies at -235°C and solidifies at -259°C.
• It is a combustible gas but does not support in burning.

Chemical properties

• Hydrogen burns in air or in oxygen with a blue flame and it produces water.
  2H₂ + O₂ → 2 H₂O
• Metals like sodium, potassium and calcium burn in hydrogen forming corresponding forming corresponding unstable metallic hydrides.
  2Na + H₂ → 2 NaH (Sodium hydride)
  Ca + H₂ → 2 CaH₂ (Calcium hydride (Hydrolith))
• When dry hydrogen is passed over heated oxide of iron, copper, lead, etc. It reduces the metallic oxides to their metals.
  Fe₃O₄ + 4H₂ → 3Fe + 4H₂O
  In above reactions, the removal of oxygen from the compound is called reduction and hydrogen which brings about reduction is called reducing agent. But the oxides of calcium, zinc and magnesium are not reduced by hydrogen.
• Hydrogen reacts with chlorine, bromine, iodine and fluorine (halogens) in various conditions to form acids.
  H₂ + Cl₂ → 2HCl (hydrochloric acid)
• Hydrogen combines with nitrogen under 200-900 atmospheric pressure, at 500⁰ C temperature and in the presence of a catalyst, iron with molybdenum as promoter to give ammonia.
  N₂ + 3H₂ → 2NH₃
• Hydrogen reacts with burning coal and forms methane.
  2 H₂ + C → CH₄(methane)

Uses of hydrogen

• It is used in manufacturing ammonia.
• Hydrogen gas is used in manufacturing vanaspati ghee.
• It is used as reducing agent because it reduces metallic oxides into corresponding metals.
• The liquid form of hydrogen is used as fuel in rockets.