[Chemistry Class Notes] Is Matter Around Us Pure? Pdf for Exam

Anything that has mass and that occupies some space is called matter. There are basically two types of matter, pure and impure substances. Almost everything that you see around you is all matter. However, the question which arises here is whether the matter around us is pure or not? Moreover, on what terms can you define the term purity? There would have been many instances where you would have come across sentences like the water is pure or the milk used to make the tea is pure. But is it right to say all this? Or on what grounds can you say that a substance is pure? Can you say that any substance is pure if it is smooth in consistency or feels soft or is white in color? Well, to answer all your questions we will be learning about the matter today, particularly the pure and impure substances and know the answer to the question “is matter around us pure”.

What are Pure and Impure Substances?

A substance is called to be in the pure form if it is made up of just one type of molecules or particles. Pure substances normally cannot be separated by the means of simple physical methods and are widely classified as elements and compounds. An element contains only one kind of particle that can be atoms or molecules. Similarly, compounds are pure substances when they consist of two or more elements that are combined in a fixed proportion by their weight. Additionally, pure compounds are easily decomposed to separate elements by using several suitable chemical methods.

A substance which is composed of different types of elements or molecules is called impure. These kinds of substances are often known to be mixtures. Mixtures are further classified as either homogeneous mixtures or heterogeneous mixtures based on their composition. They are mostly made pure by using different kinds of separation techniques.

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Characteristics of Pure Substance

Let us now look at some of the characteristics of pure substance.

1. Pure substances have a perfectly homogeneous nature.

2. Pure substances are made up of only one type of atoms or molecules.

3. Pure substances have a fixed composition.

4. Pure substances have a fixed density, melting point, boiling point etc.

Characteristics of Impure Substance

Let us look at the characteristics of impure substances now.

1. Impure substances do not have any specific properties. The properties of the resulting mixture are a result of the average properties of all its constituents.

2. Impure substances are formed when there is a physical change.

3. Impure substances have a variable composition.

4. The mixtures of the impure substances are either homogeneous or heterogeneous in nature.

Difference between Homogeneous and Heterogeneous Substances

Different States of Matter

The three different states of matter present on Earth are solid state, liquid state, and gaseous state. Let us look at each of them in detail.

1. Solids

In a solid, the particles are packed tightly together so they don’t move much. The electrons of each atom are constantly in motion, so the atoms have a small vibration, however, they are fixed in their position. Because of this, the particles in a solid have very low kinetic energy.

Solids have a definite shape, as well as mass and volume, and do not conform to the shape of the container in which they are placed. Solids also have a high density which means that the particles are tightly packed together. 

2. Liquids

In a liquid, the particles are more loosely packed than in a solid and are able to flow around each other, giving the liquid an indefinite shape. Therefore, the liquid will conform to the shape of its container.

Much like solids, liquids (most of which have a lower density than solids) are incredibly difficult to compress. 

3. Gasses

In a gas, the particles have a great deal of space between them and have a higher kinetic energy. A gas has no definite shape or volume. If unconfined, the particles of a gas will spread out indefinitely; if confined, the gas will expand to fill its container. When a gas is put under pressure by reducing the volume of the container, the space between the particles is reduced and the gas is compressed.

Is Matter Around us Pure? – Summary

As mentioned above matter is of two different kinds, pure and impure substances. You can know the products and matter around you is pure or impure by taking a look at them and their composition. Consider, for example, salt. The constituents of all the particles in the salt are the same, that is, the particles are all NaCl. They look and taste the same as well. There is no other kind of particle present in the salt except NaCl. This means that salt is a pure substance. When you talk about impure substances, they are made up of different molecules in just one substance. Consider, for example, ghee. Ghee is made up of several vitamins, amino acids, fats, etc., and is, therefore, regarded as an impure substance. All impure substances are said to be mixtures of two or more substances or molecules.