In a comprehensive school, every seventh grader must get acquainted in physics with various phenomena that can be found both in everyday life and in industrial conditions.
This article is about diffusion. Initially, this term may seem intimidating, something unusual. In fact, it is one of the most common phenomena, more precisely even to say that it constantly and everywhere takes place. Let us examine what diffusion is in physics, and at the same time we will give many examples that will make it clear: there is nothing complicated, and the topic on the school subject is quite simple and interesting.
Diffusion definition
In different sources you can find different wording, but one that does not lose its original meaning.
Diffusion is a phenomenon in which the molecules of one substance penetrate the molecules of another substance. The student may find this phrase too incomprehensible and complex. But in fact, everything is quite easy. As you know, a molecule is the smallest particle of any substance (even air, gas has it). Each molecule is interconnected by structural bonds. The denser the structure, the harder the body. Thus, the penetration of molecules of one substance into the molecules of another will be easier if the structure is the simplest or the molecules exist freely.
That is why the definition sounds like this. What is diffusion in physics? Simply put: the connection, the penetration of two substances into each other. As a result, a single whole is formed.
Gas and air
Let's start by looking at examples of simple molecular compounds like gases. The fact is that air is easiest to change. For example, you sprayed perfume in a room. Immediately or after a few seconds, the aroma is already felt. In this case, we can already answer the question of what diffusion is.
In physics, all substances are divided into three main states:
Accordingly, the gaseous state is capable of a fairly quick reaction.
Here is another example: the smell of paint spreading around during the painting of products. Car exhaust is also a diffusion in the environment, therefore, unfortunately, the environment suffers, air is polluted in large and small cities.
It is worth noting that the air is mobile, its molecules are constantly moving. Therefore, diffusion with any foreign gaseous substances occurs continuously.
Water
And now let us briefly examine what diffusion is in physics with respect to liquid substances. Imagine a vessel with water. Add a little potassium permanganate or coloring matter to it. The process can be observed until the water is completely colored. It should be noted that diffusion occurs much faster in hot water. An ordinary cup of tea or coffee can demonstrate this. If sugar is added to hot water, it will quickly dissolve. When cream is added to hot coffee, coffee and water, as well as cream, quickly merge together.
When cooking soups, broths and sauces, diffusion is also observed. It should be noted that heat treatment of food (namely cooking) occurs most often precisely because it is necessary to combine one substance with another. Suppose chicken stock does not work in cold water, because meat juice must interact with hot water.
Solid products in industry
There is such a state of substances when it is impossible to determine whether it is solid or liquid. This is not the purest substance, but the totality. For example, pancake dough, liquid clay, thick oils. What is diffusion in physics in relation to similar products? The penetration of molecules will also persist. For example, in the manufacture of alloys, plastics, various materials that are solid in nature are used in the liquid state. But when heated, they become liquid, their molecules are able to penetrate one into another, that is, there will be diffusion. Thus, there are many durable steel, plastic products, materials.
Solid Diffusion
Earlier we examined the definition of what diffusion is in physics, now we know. According to logic, there can be no diffusion in solids. This is partly true. But there is evidence that with the constant storage together of some substances, they become a single whole.
For example, if together we put lead and gold in one box so that they are closely pressed together, then after about 5 years they will connect with their surfaces. Therefore, answering the question of what diffusion is in physics, we will consider absolutely all substances, but only one state.
Chemical processes
In conclusion, it is worth noting that the phenomenon of diffusion is studied in chemistry, and even in biology. Therefore, this term can be encountered not only in physics. Chemists in laboratories constantly conduct various experiments in which a similar process can not be dispensed with. But the main topic is considered in the 7th grade. What is diffusion in physics and chemistry? This is a fairly common phenomenon in nature and in everyday life, as well as in the production of something.