UNIT 9 HYDROGEN
Hydrogen is the first element in the periodic table.
Its electronic configuration is 1s1.
Occurrence: Dihydrogen is the most abundant element in the universe. It is the principal element in the solar atmosphere.
Isotopes of hydrogen: Hydrogen has three isotopes: protium, deuterium and tritium
PROPERTIES OF DIHYDROGEN:
- Physical properties:
- It is a colourless, odourless, tasteless, combustible gas.
- It is lighter than air.
- It is insoluble in water.
- Chemical properties
- Reaction with halogens: It reacts with halogens to give hydrogen halides.
- Reaction with dioxygen: It reacts with dioxygen to form water.
- Reaction with dinitrogen: It reacts with dinitrogen to form ammonia.
- Reaction with metals: It reacts with metals to yield the corresponding hydrides.
- Reaction with metal ions and metal oxides: It reduces some metal ions in aqueous solution and oxides of metals (less active than iron) into corresponding metals.
- Reaction with organic compounds: It reacts with organic compounds to give useful hydrogenated products.
USES OF DIHYDROGEN
- The largest single use of dihydrogen is in the synthesis of ammonia which is used in the manufacture of nitric acid and nitrogenous fertilizers.
- Dihydrogen is used in the manufacture of Vanaspati fat by the hydrogenation of polyunsaturated vegetable oils like soybean, cotton seeds, etc.
- It is used in the manufacture of bulk organic chemicals, particularly methanol.
- It is widely used for the manufacture of metal hydrides.
- It is used for the preparation of hydrogen chloride, a highly useful chemical.
- In metallurgical processes, it is used to reduce heavy metal oxides to metals.
- Atomic hydrogen and oxy-hydrogen torches find use for cutting and welding purposes.
- It is used as a rocket fuel in space research.
- It is used in fuel cells for generating electrical energy.