Grade 4, Science Olympiad (CBSE) - Solution & solvent, Purification of water 

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Grade 4  |   Science  |   Solution & solvent, Purification of water, Our Environment, Olympiad, CBSE, ICSE, Maths Olympiad, Science Olympiad, English Olympiad

Solution

A mixture of 2 or more substances is called solution. One substance dissolves other.

Solvent: The substance which is dissolving other substance in itself is called solvent. e.g. Water

Solute: The substance which is getting dissolved is called solute. e.g. salt, water, sand, chalk

Thus the solution is a mixture of solute and solvent.

1) Soluble solute: solutes that dissolve completely in the solvent are called soluble solutes. e.g. sugar, salt, milk etc in water solvent.
2) Insoluble solute: solutes that do not dissolve completely in the solvent are called insoluble or suspended solutes. e.g. sand, chalk, oil etc in water solvent.

Homogeneous solution: When substances are evenly distributed throughout the mixture i.e. there is uniformity in composition throughout the mixture. e.g. Salt and water solution, sugar and water solution, air etc.

Heterogenous solution: When substances are not distributed evenly in the mixture and there are phases of low and high concentration. e.g. sand in water, cereals in milk etc.

Water purification

There are 2 types of water impurities :
1) Soluble: impurities that dissolve in water are called soluble water impurities. e.g. sugar, salt, milk etc.
2) Insoluble or suspended: impurities that do not dissolve in water are called insoluble or suspended impurities. e.g. sand, chalk, oil etc.

Sedimentation is the process by which insoluble particles settle down at the bottom of the water.

Decantation is the process by which pure water at the top is removed.

Filtration is the process when some suspended impurities are removed by passing water through a filter.

Distillation is another way of water filtration and is most effective.
During distillation, water is first evaporated so that soluble impurities are left behind and water in converted into vapours. Vapours are then condensed to convert them back to water.

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