Discovered

Oxygen was discovered by the Swede Scheele and the Englishman Priestley independently of each other during the late 18th century. For most of the 18th century, it was considered that a volatile substance, phlogiston, was emitted during all combustion. When the French chemist Lavoisier showed that metals increased their weight during combustion, those who believed in the phlogiston theory were forced to assume that phlogiston had a negative weight. Reluctantly, the phlogiston theory was abandoned

Characteristics

Oxygen, O2, lacks color, odor and taste. Liquid oxygen has a pale blue color and is paramagnetic, which means that it is weakly attracted to a magnet. Ozone, O3, which can be formed by electrical discharges or by ultraviolet light on oxygen, is chemically very active. The ozone layer found in the upper part of the atmosphere is of great importance for life on earth because it prevents large parts of the dangerous ultraviolet radiation from reaching the earth’s surface. Ozone is very toxic. The limit value in air is 0.2 mg / m3. Liquid ozone is bluish and solid ozone is black-violet. Natural oxygen is a mixture of three isotopes. Nine isotopes are known.

Use

 Part of hundreds of thousands of associations. Oxygen is important for plants and animals and for practically all combustion.

Presence

Oxygen is the most common element in the earth’s crust — about 49% by weight. In the sun, oxygen is the third substance after hydrogen and helium. The sun’s red and yellow-green aura comes from oxygen. About 2 thirds of our body and 90% of water is oxygen.

Production

 The plants release almost all the oxygen on earth. In the laboratory, oxygen can be produced by electrolysis of water or by heating potassium chlorate with magnesium dioxide as catalyst.

General information about the element hydrogen

Hydrogen is a colorless and odorless combustible gas that is the universe’s most abundant element. It is estimated that about 88% of all atoms in the universe are hydrogen atoms. Hydrogen is a very simple substance without particularly peculiar properties, but in combination with other elements it can form very strange chemical compounds. The most special is H2O (water), which should be a gas at room temperature, and which, unlike most other substances, expands when it freezes. This is due to special compounds between the hydrogen atoms in the water molecules that make them take up more space in the cold state.

Hydrogen has been used in industry for many years, for rocket engines, balloon transport and the like. But hydrogen may in the future play a far greater role for e.g. energy supply. But that energy can also be released again in, for example, fuel cells, in which hydrogen is converted into water and electricity. This principle can be used, for example, in hydrogen cars.A hydrogen car is powered by an electric motor that receives electricity via a fuel cell instead of a battery. The hydrogen car is a climate-friendly alternative to ordinary cars that run on fossil fuels and pollute with CO2.

Hydrogen is highly flammable and combines easily with oxygen to form water. When hydrogen is mixed with air, an explosive mixture is formed which can be ignited with a single spark. It is such a powerful fuel that the space shuttle’s main engines are powered by hydrogen

Brief history of hydrogen

Hydrogen was actually discovered as early as the 16th century by the Swiss physician and natural philosopher Paracelsus, but he did not understand what it was. Without the one who would then be counted as the discoverer of hydrogen is the Englishman Henry Cavendish, who was the first to isolate something he called «combustible air». This happened sometime between the years 1766 and 1781. However, the person who gave hydrogen its name was the French chemist Antoine Lavoisier. In 1783, Laviosier succeeded in producing hydrogen from water and therefore hydrogen gave the French name hydrogené (water creator), from the Greek hydro (water) and gene (I create).

Hydrogen properties, production and use

In pure form, hydrogen is a colorless and odorless gas that burns easily and reacts strongly with oxygen. A mixture of hydrogen and oxygen can form explosive gas, which gives off a powerful bang during combustion. Hydrogen is the most common substance in the world, but despite this, hydrogen is rare in pure form in the atmosphere. Hydrogen is instead present in many chemical compounds, e.g. hydrocarbons, however, the most common occurrence is in water where hydrogen is present in combination with oxygen.

A vital gas in many ways

In fact, hydrogen is necessary for all living things, not only in the form of hydrogen being one of the building blocks of the vital water or the organic compounds that make up all living organisms, hydrogen is also what allows the sun to heat the earth. Every second, the sun converts 600,000,000 tons of hydrogen into helium and the energy that radiates from its surface. Although it sounds huge, we do not have to worry, it will be five billion years before the sun has run out of all the hydrogen it contains.

Production and use

 In pure form, hydrogen can be produced from hydrocarbons or by electrolysis of water, and some examples of practical use of hydrogen are for the production of ammonia in the petroleum industry or together with nitrogen for leak detection and to store energy. The hydrogen gas burns easily and can also be used in fuel cells. In the past, hydrogen was used in balloons, but this use fell sharply after the disaster following the fire in the German airship LZ 129 Hindenburg in 1937.