Encyclopedia about Chemistry

One of the most far-reaching chemical discoveries was the invention of plastics and other synthetic materials. There are a number of different types of plastics and other synthetic materials, each with its own different properties. Many react as temperature changes. Some, however, are able to withstand changes in temperature.

These find use in situations when a material must be exposed to very high or very low temperature, for example in a heat insulator.

Nature has also been a reliable supplier of the basic materials that we human beings take for granted. In nature, calcium is one of the basic raw materials. From it, lime and limestones in their various forms can be produced, these often being used in the construction industry. Lime is also an ingredient in cements and cement mortar.

The colour of foods and foodstuffs is also the domain of chemistry. At the same time, this area of the natural sciences is living proof of the numerous uses and many-sided nature of many of the compounds that make up certain materials.

and who would have thought that our bodies, the coal and other fuels we use to heat our homes, and the bubbles in many of our drinks, are all composed of one and the same element, carbon?

Today’s wide variety of cleaning products were without exception tested in laboratories around the world. This is how we keep things clean: by using chemicals which can quickly and effectively remove stains, and make our world a brighter place to live in.

and what about transportation? Flying, either by airplane or by the precursors of what will one day be spaceships, is the result of long years of chemistry (and physics) research. This brings up a scientific truth: Chemistry, including the chemical industry, is closely related to other natural science branches, such as physics, biology and even mathematics. In many cases, these sciences are so closely related that it is impossible to separate them. That is why, together, they are called the natural sciences.

It is beyond the scope of this document to name all of the things that chemistry has done to improve our world. We can, of course, try to show some of the advances that have been made in the wonderful world of chemistry with the help of a few examples. It is, however, like the view through a narrow keyhole into a large room. It is possible to see a few of the larger features, such as where some of the furniture is placed. But the real content of the room, down to its intricate details - that is impossible to see without much closer examination. So are many of the discoveries made, thanks to chemistry, that we tend to take for granted.

Sulphur oxide is a colourless, suffocatingly toxic and poisonous gas. When it is dissolved in water, it forms sulphuric acid. Sulphur oxide is used in the production of sulphuric acid, as a bleach and as a preservative in some foods.

Sulphurous acid is a weak acid which is found in solution only. It is a product of the dissolving of sulphur oxide in water.

Sulphuric acid is produced through a process known as contact oxidation. The reaction mechanism has pure SO₂ oxidising at 500° C under the influence of a vanadium catalyst. The cooled gas is led through a 98% solution of sulphur acid. The compound SO₃ is absorbed, to create H₂S₂O₇. By diluting with water, sulphuric acid of the desired concentration is produced.

Phosphoric acids are those which come from phosphorus derived from oxygen-containing acids. Phosporic acids are relatively strong and non-volatile. They have a pleasant-smelling odour and are non-toxic. When added to some drinks, they are taste boosters, making these drinks have more intensive tastes. They are produced by dissolving phosphoric oxide in water.

Phosphates are salts of the phosphoric acid family, especially those of the ortho phosphorous acids. Because these have three hydrogens included, they can be replaced. There are, therefore, three degrees of phosphates which can be derived from this group of phosphoric acid.

Primary phosphates have just one atom of hydrogen replaced by a metal, giving the chemical formula

In the laboratory, ammonia can be produced by the reaction of a concentrated solution of sodium hydroxide and ammonium chloride.

Ammonia is easy to recognise in its gaseous state because of its distinctive odour. An indicator can be used to determine whether ammonia is present in an aqueous solution. If so, the paper indicates base. We get the same alkaline reaction when indicator paper is subjected to the effects of an ammonia pair. When reacted with hydrogen chloride, ammonium chloride is formed. This reaction can be recognised because of the formation of white smoke.

Ammonia can be synthesised from the elements nitrogen and hydrogen in what is known as the Haber-Bosch reaction. After years of experimentation, the technology finally developed, and in 1909, F. Haber and C. Bosch started getting close to their dream. A few years later, the synthesis had been performed successfully (F. Haber won the Nobel Prize in 1918 for the feat). An equilibrium reaction, in the presence of a catalyst, resulted in the formation of ammonia. In order to make the reaction work effectively, high temperature and high pressure are needed.

Ammonia reacts with water to produce the ammonium ion and a hydroxide ion. In this reaction, one atom of hydrogen bonds to the lone electron pair of the original ammonia compound NH₃. A proton, then, is transferred.

The nitrogen-containing salts found in the Earth’s crust are taken in by plants through their roots and are later used in the production of amino acids, proteins and other compounds. Plants are primary producers of organic nitrogen compounds. All animals, including the human animal, must meet their nutritional needs, in a direct or indirect way, by ingesting some form of plant material. Once used, nitrogen is freed from the compound it was included in, often when that organism’s organic material begins to decay, in the form of ammonia. Nitrifying bacteria then change ammonia to nitrates which can be reingested by plants.

Nitrogen is a vital raw material in the lives of all living organisms, if only in small doses. Animals and human beings get their nitrogen from plants, not being capable of taking it in directly from the atmosphere. Most plants take in nitrogen in the form of the ammonium ion or in nitrate ions from the ground. The nitrogen which occurs in the atmosphere is bonded by several symbiotic microorganisms (nitrogenous bacteria of legumes, fungi in the root systems of alders) and transferred into the host plant. The nitrogen dioxide which is formed in thunderstorms also makes its way into the ground. This is how nitrogen, in the form of ammonium and nitrate ions, makes its way into the food chain: through the root systems of plants. After the microorganisms that brought it into those root systems die, and nitrogen is freed from the proteins which contained it in the form of ammonia, again by the actions of microorganisms. Part of this is then once again changed by bacteria to ammonium and nitrate ions... These are once again taken in by plants... Other ammonium is used by the denitrifying bacteria, changing it to molecular nitrogen, which is then returned to the atmosphere.