LESSON FIVE Chemistry and Matter

Why study chemistry? An important reason is indicated in the foregoing statement by Benjamin Franklin—it is through chemistry and her sister sciences that the power of man, of mind, over matter is obtained. Nearly two hundred years ago Franklin said that science was making rapid progress. We know that the rate of progress of science has become continually greater, until now the world in which we live has been greatly changed, through scientific and technical progress, from that of Frank1in’s time.

Science plays such an important part in the modern world that no one can now feel that he understands the world in which he lives unless he has an understanding of science.

The science of chemistry deals with substances. At this point in the study of chemistry we shall not define the word substance in its scientific sense, but shall, assume that you have a general idea of what the word means. Common examples of substances are water, sugar, salt, copper, iron, oxygen-you can think of many others.

A century and a half ago it was discovered by an English chemist, Sir Humphry Davy, that common salt can be separated, by passing electricity through it, into a soft, silvery metal, to which he gave the named sodium, and a greenish-yellow gas, which had been discovered some time earlier, named chlorine. Chlorine is a corrosive gas, which attacks many metals, and irritates the mucous membranes of the nose and throat if it is inhaled. That the substance salt is composed of a metal (sodium) and a corrosive gas (chlorine) with properties quite different from its own properties is one of the many surprising facts about the nature of substances that chemists have discovered.

A sodium wire will burn in chlorine, producing salt/. The process of combination of sodium and chlorine to form salt is called a chemical reaction. Ordinary fire also involves a chemical reaction, the combination of the fuel with oxygen in the air to form the products of combustion. For example, gasoline contains compounds of carbon and hydrogen, and when a mixture of gasoline and air burns rapidly in the cylinders of an automobile a chemical reaction takes place, in which the gasoline and the oxygen of the air react to form carbon dioxide and water vapor (plus a small amount of carbon monoxide), and at the same time to release the energy that moves the automobile.

Carbon dioxide and carbon monoxide are compounds of carbon and oxygen, and water is a compound of hydrogen and oxygen.

Chemists study substances in order to learn as much as they can about their properties (their characteristic qualities) and about the react ions that change them into other substances. Knowledge obtained in this way has been found to be extremely valuable. It not only satisfies man’s curiosity about himself and about the world in which he lives, but it also can be applied to make the world a better place to live in, to make people happier by raising their standards of 1ivng, ameliorating the suffering due to ill health, and enlarging the sphere of their activities.

Let us consider some of the ways in which knowledge of chemistry has helped man in the past and may help him in the future.

It was discovered centuries ago that preparations could be made from certain plants, such as poppies and coca, which, when taken by a human being, serve to deaden pain (are analgesics).

From these plants chemists isolated pure substances, morphine and cocaine, which have the pain deadening property. These substances have, however, an undesirable property, that of inducing a craving for them that sometimes leads to drug addiction. Chemists then investigated morphine and cocaine, to learn their chemical structure, and then made in the laboratory a great numbers of other substances, somewhat similar in structure and tested these substances for their powers of deadening pain and of producing addiction. In this way some drugs that are far more valuable than the natural ones have been discovered; substances with 10 000 times the potency of morphine have been made.

A related story is that of the discovery of general anesthetics. In 1800 Humphry Davy, as a young man just beginning his scientific career, tested many gases on himself by inhaling them. (He was lucky that he did not kill himself, because one of the gases he inhaled is very poisonous.) He discovered that one gas produced a state of hysteria when inhaled, and that people under the influence of this gas, which was given the name laughing gas, seemed not to suffer pain when they fell down or bumped into an object. He suggested its use in surgery in the following words: “As nitrous oxide, in its extensive operation, seems capable of destroying physical pain, it may probably be used with advantage in surgical operations.” His suggestion, however, remained unheeded for nearly half a century. Then in 1844 nitrous oxide was used for the extraction of a sooth and two years later the first surgical operation under diethyl ether anesthesia was carried out. Ether, chloroform, and nitrous oxide were soon brought into general use. The discovery of anesthesia was a great discovery, not only because it relieves pain, but also because it permits delicate surgical operations to be carried out that would be impossible if the patients remained conscious.

The rubber industry may be mentioned as an example of a chemical industry. This industry began when it was discovered that raw rubber, a sticky material made from the sap of the rubber tree, could be converted into vulcanized rubber, which has superior properties (greatly increased strength, freedom from stickiness), by mixing it with sulfur and heating it. During recent years artificial materials similar to rubber (called synthetic rubber) have been made, which are in many ways better than natural rubber. The synthetic rubbers are made from petroleum or natural gas.

The steel industry is another great chemical industry. Steel, which consists mainly of the metal iron, is our most important structural material. It is made from iron ore by a complex chemical process.

Chemistry plays such an important part in the life of twentieth-century man that this age may properly be called the chemical age.

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