Page 151 - ICSE Chemistry 8

The most important compound of hydrogen is water (H O) that covers 70% of the earth’s surface. Hydrogen
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combines with other elements to form compounds such as acids, bases, hydrocarbons, carbohydrates,
proteins and fats. The occurrence of hydrogen on the earth in various compounds is given in Table 7.1.

Table 7.1: Compounds of Hydrogen on the Earth

Combination of hydrogen with Compounds Occurrence
Oxygen Water (H O) Oceans, seas, rivers, lakes, ponds, water vapour in
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air, underground water, etc.

Carbon Hydrocarbons Oil, petroleum and natural gas

Carbon, oxygen and nitrogen Organic compounds Animal and vegetable matter

Chlorine, sulphur, nitrogen and oxygen Acids, alkalis Prepared in laboratory

DISCOVERY OF HYDROGEN

In 1671, Robert Boyle found a gas during a reac on Know Your Scientist
between iron fi lings and dilute acids. He noted that
Henry Cavendish was an
these fumes were highly fl ammable.
English chemist and physicist.
In 1766, Henry Cavendish recognised hydrogen as He was born on October 10,
an element. He then called it ‘infl ammable air’ or 1731 in Nice, France. He is
‘phlogiston’. He observed that it is dis nct from credited with recogni on of
other combus ble gases. He studied the proper es hydrogen as an element and the discovery of
of hydrogen and found that the only product we get composi on of water.
on burning hydrogen is water.

In 1781, Antoine Lavoisier, a French chemist named this gas as hydrogen. In Greek hydro means water and
genes means forming. So hydrogen means forming water.

Thirst for Knowledge

It is believed that Paracelsus, a German-Swiss alchemist had studied hydrogen in the 16th century. He
found that an infl ammable gas was produced when a metal was dissolved in an acid.

PREPARATION OF HYDROGEN
Know Your Scientist
In laboratories and industries, hydrogen is prepared
Antoine Lavoisier was born on August 26,
from its compound as it is not available in free
1743 in Paris, France. He named both oxygen
state. Hydrogen is obtained by its displacement
and hydrogen. He demonstrated the role of
from compounds like water, dilute acids and alkalis
oxygen in rus ng of metal as well as role of
by more reac ve metals. Such reac ons are called oxygen in animal and plant respira on.
displacement reac ons.

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