TOPIC 2: HYDROGEN | CHEMISTRY FORM 1
Hydrogen is the lightest of all the elements. There is very little hydrogen in the earth’s atmosphere. Hydrogen is so light that its molecules are not held by the earth’s gravity and they diffuse into space.
Overall, it is the most common element in the universe. It is probable that is forms about 90% of the total mass of the universe. It is believed that the sun composes almost of hydrogen and helium. Hydrogen occurs naturally in air as hydrogen gas. It also occurs in combined state in water, acids, petroleum, and natural gas and in almost all organic substances
(proteins, carbohydrates, fats, etc.)
Preparation and Properties of Hydrogen
The Preparation of Hydrogen Gas in a Laboratory
Explain the preparation of hydrogen gas in a laboratory
Hydrogen is most commonly prepared in the laboratory by the action of dilute mineral acids on certain metals. The most convenient way to prepare
hydrogen in the laboratory is by addition of dilute hydrochloric acid on
zinc granules. Zinc and hydrochloric acid are chosen because they
produce the gas at a steady rate.
The gas may be collected by downward displacement of water. But when the gas is required free from moisture it is passed through water to remove
first, any hydrogen chloride gas and then through concentrated sulphuric
acid to remove moisture before being collected by upward delivery. The
gas is prepared by upward delivery method because it is lighter than air
and is soluble in water.
The Properties of Hydrogen
Explain the properties of hydrogen