Pure substance and mixture. Chemistry

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2018-04-16 09:00:32

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In 8th grade students learn in the course of chemistry of pure substances and mixtures. Our article will help them to understand this topic. We will tell you what the substance is called pure, and which – mixtures. Have you ever thought about the question: “is There an absolutely pure substance?” Perhaps the answer will surprise you.

pure substance

Why this subject is taught in school?

Before considering the definition of “pure”, you need to deal with the question: “what kind of substance we actually have a business – with a pure or a mixture?”

At all times the purity of the substance was excited not only researchers and scientists but also ordinary people. What we usually mean by this concept? Each of us wants to drink water free of impurities of heavy metals. We want to breathe fresh air that is not polluted by exhaust fumes of vehicles. But can we call unpolluted air and water pure substances? From the point of view of science – not.

What mix?

Thus, the mixture-is a substance that contains molecules of several types. Now think about the composition of the water, which flows from the tap – Yes, it has a lot of impurities. In turn, the substances that make up a mixture are called components. Let's consider an example. The air we breathe-a mixture of different gases. The components included in its composition-oxygen, nitrogen, carbon dioxide, and so on. If the mass of one component is ten times smaller than the mass of the other, such a substance called a mixture. Often found in nature in the air, which is contaminated with impurities of hydrogen sulfide. This gas has a smell of rotten eggs and is poisonous to humans. When resting on the banks of the river make a fire, it pollutes the air with carbon dioxide, which is also dangerous in large amounts.

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Very ingenious guys may have already raised the question: “more common – pure substance or mixture?” the Answer to your question: “basically everything that surrounds us – mixture”.

In Such an amazing way nature works.

pure substances and mixtures

A Few words about the types of pure substances

At the beginning of this article we promised to tell you about whether there are substances with absolutely no impurities. Do you think there are? About the tap water we have already spoken. Will nemoget to contain impurities of spring water? The answer to this question is simple: absolutely pure substance not found in nature. However, in scientific circles to talk about the relative purity of the substance. It sounds like this: “the Substance is pure, but with the caveat". For example, it may be technically clean. Black and purple inks contain impurities. If they cannot be detected using a chemical reaction, that substance is called chemically pure. This is the distilled water.

About cleanliness

So, it's time to talk about pure substance. It is a substance that consists of particles of only one kind. It turns out that it has special properties. It has another name: the individual substance. Let's try to characterize the properties of pure water:

  • Individual substance: distilled water;
  • Boiling point – 100°C;
  • Fusion temperature – 0°C;
  • This water has no taste, odor and color.

pure substances in nature

How to separate substances?

This issue is also relevant. Very often in life and at work (most) people parts matter. So, for example, milk cream is formed, which can be collected from the surface if to apply a method of settling. During the refining of oil man produces gasoline, jet fuel, kerosene, machine oil and so on. At all stages of processing people applies different methods of separating mixtures, which depend on the physical state of matter. Look at each of them.

Filtering

This method is used in the case when there is a liquid substance that contains insoluble solid particles. For example, water and river sand. Such a mixture of people flows through the filter. Thus, the sand stays in the filter and clean the water quietly goes in after. We rarely give it much thought, but every day in the kitchen, many people let the water flow from the tap through the purifying filter. So to some extent you can consider yourself scientists.

what is more common pure substances or mixtures

Advocacy

This method, we said a few words just above. But let's consider it in more detail. This technique the chemists used in the case when it is necessary to separate the suspension or emulsion. For example, if clean water has penetrated the vegetable oil, the resulting mixture should be shaken, then let it stand for a while. After that, people observe a phenomenon, when the oil film will cover the water.

In the laboratory, chemists use another method, which is called a separatory funnel. When using this method of cleansing the dense fluid permeates into the container, and the fact that it is easier – remain.

A Method of sedimentation has a major drawback – low speed of the process. In this case, it takes a long time for the formation of a precipitate. In industrial plants this method is stilluse. The engineers can design special designs, which are called "settlers".

Magnet

Each of us at least once in life was playing with a magnet. Its an amazing property to attract metals seemed magical. Resourceful people have thought to use a magnet to separate mixtures. For example, splitting wood and perhaps iron filings with a magnet. But it is worth considering that not all the metals he can pull, he is subject to only those mixtures that contain ferromagnetic materials. These include Nickel, terbium, cobalt, erbium, and so on.

chemistry pure substances and mixtures

Distillation

The term has Latin roots, means "drops off". This method represents the separation of mixtures based on differences in boiling points of substances. This method will help to separate water and alcohol. The last substance evaporates at +78°C. When the vapors touch the cold walls and surfaces, a pair congenerous, turning into a liquid substance.

In heavy industry this method produce oil products, pure metals, and a variety of fragrances.

Is it Possible to separate gases?

We talked about pure substances and mixtures in liquid and solid state. But what if you need to carry out the separation of gas mixtures? The bright head of the chemical industry today engage in more physical methods of separation of gaseous mixtures:

  • Condensing;
  • Sorption;
  • Membrane separation;
  • Delegacia.

types of pure substances

So in our article we reviewed the concept of pure substances and mixtures. We have found that is more common in nature. Now you know the different ways of separating mixtures-and some of them can prodemonstrirovat themselves, like a magnet. We hope that our article was useful to you. Learn the science today, so that tomorrow she can help you solve any problem – both at home and in the factory!


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Alin Trodden - author of the article, editor
"Hi, I'm Alin Trodden. I write texts, read books, and look for impressions. And I'm not bad at telling you about it. I am always happy to participate in interesting projects."

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