Characteristics of a Pure and Impure Substances

In simple terms, matter can be defined as anything and everything that has a mass and occupies space. Everything from the air you breathe, the water you drink, or the clothes you wear comes under the category of matter. It is made up of an elementary particle referred to as an atom. A further matter is subdivided into two primary categories which are – 

• Pure substances 

• Impure substances 

Pure and impure substances are different from one another and have distinctive characteristics. Now, let’s look into them in detail to get a clear understanding of Characteristics of a pure and impure substances. 

What are pure substances? 

When single types of atoms are combined together, it results in the formation of pure substances. As a result, these substances possess homogeneous chemical compositions and hold a fixed structure and chemical properties. Common examples of pure substances are  

Sugar (C₁₂H₂₂O₁₁), Chlorine (Cl₂), Baking soda (NaHCO₃), Oxygen (O₂), etc. Further, pure substances are divided into two major categories. These include – 

Elements 

Elements are referred to as pure substances as they only contain a single type of atom. Presently, there are about 118 elements in the periodic table. Some of the common elements are silver (Ag), gold (Au), sulphur (S), hydrogen (H), and so on. 

Compounds 

When more than one element combines chemically in the fixed ratio, a compound is formed. Pure compounds can be chemically transformed into newer substances. Some common examples of these substances include salt (NaCl), carbon dioxide (CO₂), water (H₂O), and so on. 

Characteristics of pure substances 

The following are the Characteristics of a pure substances –

• Pure substances have homogeneous chemical compositions.

• These have constant structures and unique chemical properties. 

• They possess a defined melting and heating point. 

What are impure substances? 

Impure substances, also known as mixtures, are another type of matter formed through different kinds of molecules or atoms. The stature of these is not fixed or constant, unlike pure substances. They can be broken down into pure substances with the help of purification methods such as sublimation, filtration, crystallisation, and so on. Further, impure substances are classified into two major categories – 

Homogeneous mixture

Homogeneous mixtures can be described as the type of mixture where the substances mixed together are distributed uniformly throughout the mixture. These have the same composition throughout the volume. Its particles cannot be seen through the naked eyes. The amount of substances present in every sample of a homogeneous mixture is always the same. The most common examples of Homogeneous mixtures include sugar water, rainwater, air, vinegar, vodka, and so on. 

Heterogeneous mixture

Heterogeneous mixtures are the second type of mixtures in which different substances or components are mixed together whose particles are clearly visible under the microscope. Its components can be easily identified through the naked eye. Examples of heterogeneous mixtures include mud water, concrete, chocolate chip cookies, rocks, sand in water, salad, coffee, sugarcane juice and so on.

Here is a quick difference between a homogenous mixture and the heterogeneous mixture for the ease of revision –  

Characteristics of impure substances 

The following are the characteristics of impure substances – 

• Impure substances have heterogeneous chemical compositions. 

• These substances are formed because of chemical changes. 

• These can be transformed into pure substances by purification methods such as crystallisation, filtration, sublimation, and so on. 

• Impure substances are further divided into homogeneous and heterogeneous mixtures.

Difference between pure and impure substances 

Below, we have curated a table that signifies the difference between a pure and impure substance. Let’s have a look – 

Conclusion 

Matter is one of the most fundamental topics of Chemistry. Further, it is divided into two major parts including Pure substances and impure substances. Pure and impure substances have distinctive compositions and properties. While pure substances are made of single atomic particles, impure substances consist of different atoms. 

Everything from the air you breathe, the water you drink, or the clothes you wear comes under the category of matter. These notes on the Characteristics of a pure and impure substances provide a detailed understanding of these substances. Also, the pure and impure substances difference table gives a quick glimpse for easy revision.