What is Pure Substance – Definition

Everything around us is made up of some or the other states of matter. Commonly, we distinguish matter as something that acquires space and has some weight. These states can be solid, liquid and gas. The matter is present in various forms on the planet. We can also deduce that as a substance. A substance can pertain to that state of matter which has a distinctive composition and specific properties. Further, we can classify them into two distinctive categories of pure substances and impure substances (mixtures). So, what is a pure substance and an impure substance?

What is meant by a substance?

Substance correlates to the state of an object which has a distinct composition and specific properties. The substances have two categories namely, pure substances and impure substances (mixtures). 

There are various distinctive properties of a substance. Some of them are: 

1) A substance is a form of matter that has distinct compositions and properties. 

2) Unlike the mixtures, we can separate the elements present in a substance by physical processes. 

3) Compositionally, the substance comprises atoms and molecules that are responsible for its state. 

4) As the property of matter says, the substance should also occupy some space and has to have some weight. 

Some examples of substances are iron, sugar, sodium chloride, hydrogen, oxygen, gold, silver and methane. Under this, the pure substances examples are Sugar, Sodium Chloride and Methane. On the other hand, the examples of mixture or impure substances are seawater (formed from the combination of salts and mixture), ink (assortment of different colored dyes), crude oil (combination of organic compounds) and dry air (combination of different types of gases present in the environment).

What is a Pure Substance? 

Pure Substances pertain to those structures of substances that are pure and are made up of only one type of particle. It should also be noted that the structure and the composition of the pure substances remain constant and fixed throughout, even if something is mixed from the outer surrounding. Pure substances examples are Gold, Water, Saline solution, Brass, Ethanol, Vinyl, Helium, Bronze, Iron, Diamond, Saline Solution, Sugar, Sodium Chloride and Methane. 

Phases of Pure Substance 

There are three distinct phases of pure substances namely, solid, liquid and gas. All these phases of pure substances have different molecular arrangements, which decide the shape which the matter will be converted into. 

1) Solid: 

The presence of molecules in a solid is tight and has a high degree of attraction. Molecules in a solid move only in an oscillation way. 

2) Liquid: 

If we talk about the liquid state, the molecules here have a lesser degree of attraction, as compared to the solid-state of the substance. The position of the molecules differs a bit in this state. 

3) Gas

The least degree of attraction between the molecules is found in the gaseous state of matter. They are characterised by constant movement from one place to another. 

Characteristics of Pure Substance

1) Pure Substances are majorly characterised by their property of homogeneity where only one kind of element is found in its composition. 

2) Being homogeneous, the pure substances have a uniform composition throughout the whole substance. 

3) As the elements present in a pure substance do not change its composition and properties, the boiling and melting point also doesn’t have any kind of change in it.

4) While mixing various pure substances, one can always get predictable products out of that mixing process. 

Types of Pure Substances 

Pure Substances can also be categorised further into two categories of elements and compounds. 

1) Elements

Elements refer to those pure substances that cannot be disassembled into different simpler substances as they are composed of only one kind of atoms and molecules. Breaking process cannot be done by either physical and chemical processes. One can understand this with an example of metal, gold, which if broken gives us gold only. Thus, it is a type of element under the category of pure substances. 

Characteristics of Elements

1) Breaking process cannot be done by either physical and chemical processes such as the heating of the substance, electrifying the substance and many other chemical processes. 

2) Unlike the compounds that have the smallest unit as molecules, the smallest unit of the elements are the atoms that cannot be broken further. 

3) All the Elements occupy an intense melting and boiling point that makes them different from each other. 

4) Examples of elements are iron, aluminium, sulphur, gold and silver. 

2) Compounds 

Compounds are substances that are composed of two or more components that are incorporated with the assistance of the chemical outcomes of the elements assembled in a continual proportion. The tiniest item we get from the combination after breaking it is the molecule of the combined substance and not the individual components. Notably, the configuration of the combination is understood from its formula that gives an account of all the elements present in the compound, with its subscript exemplifying the number of atoms of that component in the compound. 

Characteristics of a compound  

1)Elements that are incorporated to form a combination lose some of their individual properties and the compound gains some fresh specific properties. 

2) During the arrangement of a compound, the energy existing in the components undergoes a vital change. 

3) Elements can only be segregated from a combination with chemical reactions, physical responses do not influence it. 

4) Elements and the compound formed from their chemical effects may retain distinct melting and boiling points.

5) Examples of some of the compounds present around us are Methane, Dioxide Glucose and Copper sulphate. 

Conclusion

Thus, a substance can pertain to that state of matter which has a distinctive composition and specific properties. It is divided into two types of pure and impure substances. Notably, we can categorise pure substances even further into elements and compounds. Some examples of pure substances are Gold, Water, Saline solution, Brass, Ethanol, Vinyl, Helium, Bronze, Iron, Diamond, and Saline Solution. 

Elements refer to those pure substances that cannot be disassembled into different simpler substances as they are composed of only one kind of atoms and molecules. On the other hand, compounds refer to those pure substances that are composed of two or more components that are incorporated with the assistance of the chemical outcomes of the elements assembled in a continual proportion.