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PURE SUBSTANCES AND MIXTURES

Any substance or form of matter having constant properties and constant composition is called Pure Substance. Elements and compounds are the two main pure substance types. They are formed only with one type of particle with either a definite or fixed structure. Iron, steel, copper, gold, water are examples of pure substances.

TYPES OF PURE SUBSTANCE MATERIALS

Elements: Elements are simpler in form. These substances cannot be simplified or broken down any further. They cannot get transformed into another element with the help of any method, chemical or physical. Metals, non-metals or metalloids fall into this category. Some examples can be Gold and Steel. 

Compounds: Compounds also belong to the pure substance group. They are created when more than one element is combined or fused under a chemical act using a definite ratio of the atoms present. The compound substance can be separated with the aid of chemical methods to get the individual elements. For example, Water (H2O) is a compound.

MIXTURE

A mixture is a material that is formed by fusing more than one substance using a physical method. A mixture can be usually brought back into its original simple components. Impure substances can also be referred to as mixtures. Examples of mixtures are air, mineral oils, etc.

It is different from a chemical compound because mixtures are separated into substances with the help of physical processes like filtration and distillation. Mixtures have different compositions, whereas compounds have a definite and constant composition. There is only a minimum or no change in energy when a mixture is formed.

Examples of Mixtures:

Crude oil: It consists of some organic compounds, especially hydrocarbons.

Air: It consists of different gases like Nitrogen, Oxygen, Carbon Dioxide, Neon, etc.

Gun powder: It consists of Potassium Nitrate, sulphur and Carbon. 

Ink: It consists of coloured dyes which can be separated by chromatography.

Blood: It contains numerous abundant substances like red and white blood cells; plasma, glucose, albumin, water and so on.

Mineral Oils: It contains branched, straight-chained and cyclic heavy alkanes.

Soda: It contains sugar, water and added flavours.

PROPERTIES OF MIXTURES

  • It is made of impure substances. 
  • There is no formula for a mixture. 
  • It can be fixed in any ratio.
  • It can be of either a homogeneous or heterogeneous type.
  • The constituents of a mixture can be separated using physical methods easily.

TYPES OF MIXTURES

Mixtures can be divided into two groups, homogeneous and heterogeneous. The word ‘Homo’ means ‘same,’ and ‘Hetero’ means ‘different’.

A homogeneous mixture has the same proportion and properties in its mass throughout. Each unit of a Homogeneous mixture is similar to its other units. 

Examples:

  1. Air: Even though the air is composed of several molecules, they are uniform in the mixture and belong to the same phase. 
  2. Sugar and water solution: Homogeneous mixture is made of more than one chemical substance. When sugar is mixed well in water and blended well, it is liquefied, and the resulting concoction is all the same. 

A heterogeneous mixture possesses different proportions and properties in several parts, which means that the properties will not be similar in all parts of the mixture.

Examples:

  1. Mixture of Oil and Water: In this mixture, oil and water can be identified separately, and their properties are different. 
  2. Mixture of sugar granules and sand: If some sugar and sand are mixed well in a jar and shaken, the concoction will not be the same in all parts of the mixture. It is a common case that sand gets occupied at the bottom and sugar at the top. Because the properties of sugar and sand are different, they can be found and separated by physical methods. 

Differences between Homogeneous and Heterogeneous mixture:

  1. Homogenous mixtures are uniform in composition, whereas the composition of heterogeneous mixtures may vary.
  2. Homogenous mixtures result in a similar phase, whereas Heterogeneous substances are identified with two phases with differences in layers.
  3. Homogeneous mixtures cannot be separated further, whereas heterogeneous mixtures can be separated. 
  4. The components of a homogeneous mixture are not visible to the naked eye, whereas, in Heterogeneous mixtures, they are visible. 

General Differences:

  • A pure substance has fixed chemical and physical properties, whereas Mixtures do not have a fixed set of such properties. 
  • A pure substance has constant chemical and physical properties, whereas mixtures have different chemical and physical properties.
  • A pure substance is made of several elements, whereas Mixtures are made of more than one substance.
  • A pure substance is simpler in their form, and therefore, cannot be split or separated with the aid of any physical methods. However, mixtures are separated by various methods of separation like filtration, evaporation, etc.
  • A pure substance can be categorised into elements and compound substances, whereas mixtures are categorised into homogeneous and heterogeneous types.
  • An example of a pure substance includes compounds like pure water, gases like Hydrogen and Helium, and metals like gold and steel. 
  • Examples of mixtures include a mixture of sugar and sand, water and oil, etc.

Conclusion

A pure substance and a mixture vary significantly from each other. With the extensive explanation provided here, the differences between the two must have become clear. So, now, think of some other liquids not mentioned here and try to identify whether it is a pure substance or a mixture.

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