Link to the lesson

The occurrence of hydrogen in nature

Hydrogen is the most widespread element in the universe – it is the main component of stars. On Earth, it occurs in trace amounts, in natural and volcanic gas, however it forms numerous compounds, e.g. water, proteins, hydrocarbons, sugars.

Hydrogen is the element that was recorded in the periodic table as first element but it does not belong to any group. It has the smallest atomic mass, due to which it is the lightest substance in the world in all states of matter *(as gas 0.00009 g/cmIndeks górny 3³, as liquid 0.07 g/cmIndeks górny 3³ and as solid 0.08 g/cmIndeks górny 3³ – its density in each of the states of matter is the smallest in comparison with other substances). Hydrogen forms diatomic molecules.

Obtaining hydrogen and testing its properties

Hydrogen is a combustible gas. Pure hydrogen combusts peacefully. The ignited fire torch inserted into the test tube with pure gas formed as a result of the reaction combusts peacefully. Hydrogen mixed with a small amount of air combusts with a characteristic sound.

$\text{Zn + 2HCl → Zn}{\text{Cl}}_{\text{2}}\text{+}{\text{H}}_{\text{2}}\text{↑}$

$\text{zinc + hydrochloric acid → zinc chloride + hydrogen}$

$\text{2}{\text{H}}_{\text{2}}\text{O → 2}{\text{H}}_{\text{2}}\text{ +}{\text{ O}}_{\text{2}}$

$\text{water → hydrogen + oxygen}$

Hydrogen is a colourless, odourless gas, slightly soluble in water, it is the element with the lowest density, about 14 times lighter than air. It is a combustible gas – in pure form it combusts with a pale blue flame but does not support combustion. The mixture of hydrogen and oxygen under the influence of heating or sparks combusts violently – it is oxyhydrogenoxyhydrogenoxyhydrogen, formerly called Knallgas.

Applications of hydrogen

Hydrogen is a raw material for the synthesis of ammonia used in the industry for the production of artificial fertilizers. As a coolant, it is used for freezing food products. Formerly it was also used to prepare artificial ice rinks.

Hydrogen is used in hydrogen‑oxygen burners for precise metal cutting and welding, among others by jewellers. In the food industry, it is used in the margarine production process, and in the pharmaceutical industry – for the production of medicines.

Currently, a special type of battery is often used, called a fuel cell (which converts chemical energy into electricity). Liquid hydrogen is also used as a fuel for space shuttles.

Summary

• Hydrogen is the most widespread element in the universe. It creates diatomic molecules in the free state.

• Pure hydrogen combusts but it does not support combustion. It is a colourless, odourless gas of the lowest density, about 14 times lighter than air. With oxygen, it forms an explosive mixture.

• It is used for the production of ammonia, hydrochloric acid and margarine and as an ecological fuel.

Key words

Hydrogen, the lightest gas, diatomic molecule, oxyhydrogen

Glossary