Importance of Chemistry
A certain amount of knowledge of chemistry is eminently useful in almost every walk of life. An intelligent knowledge of the chemistry involved in the processes of the kitchen, the dairy, the dye-house, the farm, or the manufactory, places the possessor engaged in any of these processes on a different level from the rule-of-thumb worker, who is as ignorant of the reason for adopting a particular method as he is of the properties of the materials he employs.
Technical chemistry deals especially with the application of the principles and processes of chemistry to the arts and manufactures, and it is to those who are engaged in manufactures of almost every kind that a knowledge of chemistry is a particular advantage.
It is not a question of expediency alone, but one of absolute necessity that a technical education, including chemistry as one of its principal subjects, should form not the least important part of the equipment for his work of any artisan who is to excel in his employment in intelligence and skill.
What is chemistry?
Chemistry is that branch of science which treats of the intimate composition of matter, and the changes produced in it when subjected to particular conditions—such as temperature, pressure, mass, light, catalysis, etc.
How does chemistry differ from physics?
The two branches, physics and chemistry, overlap a great deal, it being very difficult to draw the line of demarcation between them, particularly in the higher stages of the physical and chemical changes of matter.
For example, a steel needle rubbed on a magnet in a definite way undergoes physical change by means of which it acquires the power of the magnet. On the other hand, a match rubbed on a match-box undergoes a chemical change by means of which flame is produced. Thus it is possible to make a distinction between the sciences of physics and chemistry. A chemical change involves some alteration in the essential nature of the substance. The match having been ignited has undergone a permanent change, whereby it is no longer combustible. The physical change quoted above involves no alteration in the substance itself, and the acquired property is further only temporary and can be continually lost and reacquired.
The difficulty occurs in this fact, however, that every chemical change is accompanied by physical change, and the physical change may often be the only sign that chemical change has taken place.
What are the chief divisions of chemistry?
Organic and Inorganic Chemistry.—There are two great divisions in the science of chemistry, organic and inorganic. The branch which is best known is that of inorganic chemistry, which covers the chemistry of all the purely mineral substances. Organic chemistry has to do primarily with that of substances obtained from animal or vegetable sources. Now, however, it has resolved itself into the study of the compounds of carbon, always bearing in mind the fact that many carbon compounds have no organic origin, and therefore really fall outside the scope of organic chemistry.
The fundamentals of both branches are the same, and the real reason for the division is the number of the carbon compounds and their [881] highly complex character. It is in this realm that the graphic formula is of most service, and in its organic branch chemistry most nearly approaches biology.
The branch of inorganic chemistry which treats of the composition, etc., of naturally occurring minerals, receives the title of mineralogical chemistry.
Physical Chemistry explains processes, formulates laws for these processes, and is divided within itself again into electro-chemistry and thermo-chemistry, etc. One branch of physical chemistry in which great strides have been made, is the study of the general properties of gases. But it is really as much in the realm of physics as it is in the realm of chemistry.
The study of the chemical nature of substances entering into the constitution of the animal organism, and the chemical changes taking place during the life processes of animals, forms the domain of physiological chemistry.
The investigation of the influence of soils, and manures, etc., of different compositions, upon vegetable life, and the chemical principles underlying the art of agriculture, are included in the province of agricultural chemistry.
Pharmaceutical chemistry deals with the nature and mode of preparation of the various drugs, ointments, etc., employed for medicinal purposes.
The science in its relations to the arts, manufactures, and industrial processes is embraced in the wide titles of technical and applied chemistry.
What is the difference between theoretical and practical chemistry?
There are in every science two great divisions. These are known as the “theory” and the “practice” (or, as they are sometimes called, the science and the art). The theory of any science is that part of it which forms the answer in any case to the question “Why?” The practice in the same way answers to the question “How?”
If we find, for example, that by putting a fire under a vessel of water, the water gradually begins to boil, as we say, “boils away,” we have learned something that relates to practice. We have learned how to change water into vapor. It is not necessary that we should know why the result is brought about, so long as we are satisfied with the result alone.
But as soon as we begin to wish to bring about any result in the best possible way, we must inquire why a certain course of action causes the result; and in the case of the water, we ask why heat should make water boil and then disappear. The answer to the question “How?” is usually a simple one. It can be found out by experiment. Once having found out, we may usually repeat the work as often as we choose.
But the question “Why?” lies deeper, and sometimes cannot be answered at all. The answer to it is in all cases merely a guess—an attempt to explain more or less fully and satisfactorily. If we find that our explanation or theory makes it possible to foretell what will happen in new cases, then we may safely trust it and believe in it.
Give a clear, succinct outline of the essentials of theoretical chemistry.
The whole matter of molecules and atoms is one of theory. None of our senses can enable us to know directly either molecules or atoms. We can only imagine that they exist, and then give reasons why their existence makes clear to us the action of elements or of compounds one upon the other.
But in a course of descriptive chemistry, a good knowledge of theoretical chemistry is necessary in order to fully understand all that will be taken up.