JSS 2: HYDROGEN

                        HYDROGEN 

Hydrogen is a non-metallic element with the chemical symbol H and atomic number 1. It is the lightest and most abundant element in the universe.

           Occurrence of Hydrogen

Hydrogen occurs:

I. In water (H₂O).

II. In acids e.g. hydrochloric acid (HCl) and sulphuric acid (H₂SO₄).

III. In hydrocarbons such as petroleum and natural gas.

IV. In living organisms.

V. In the Sun and other stars, where it is the main fuel for energy production.

Physical Properties of Hydrogen

1. It is a colourless, odourless and tasteless gas

2. It is the lightest known gas.

3. It is less dense than air.

4. It is slightly soluble in water.

5. It is highly flammable.

6. It exists as diatomic molecules (H₂)

     

            Isotopes of hydrogen

Isotopes are atoms of the same element that have the same atomic number but different mass number. 

The three isotopes of hydrogen are:

1. Protium  (¹₁H)

2. Deuterium (²₁H or D)

3. Tritium (³₁H or T)

Chemical Properties of Hydrogen

1. Hydrogen burns in oxygen with a pale blue flame to produce water.

        2H₂ + O₂→ 2H₂O

2. It reacts with chlorine to form hydrogen chloride.

         H₂ + Cl₂→ 2HCl

3. It acts as a reducing agent by removing oxygen from some metal oxides.

         CuO + H₂ → Cu + H₂O

Laboratory Preparation of Hydrogen

Hydrogen is prepared by reacting zinc granules with dilute hydrochloric acid or dilute sulphuric acid.

Equation:

I. Using hydrochloric acid:

Zn + 2HCl → ZnCl₂  + H₂

II. Using sulphuric acid:

Zn + H₂SO₄ → ZnSO₄   + H₂

                 Test for Hydrogen

Hydrogen burns with a 'pop' sound, when a lighted splint is brought close to it

                Uses of Hydrogen

1. Manufacture of ammonia for fertilisers.

2. Hydrogenation of vegetable oils to produce margarine.

3. Used as fuel for rockets and spacecraft.

4. Fuel cells for generating electricity.

5. Welding and cutting metals.

6. Production of hydrochloric acid.