Page 83 - ICSE Chemistry 6

WATER—A UNIVERSAL SOLVENT

Water can dissolve a large number of solid, liquid and gaseous substances in it. In fact, no other solvent
can dissolve as many solutes in it as water. Therefore, it is commonly known as universal solvent.

Solute, Solvent and Solution

A substance that gets dissolved in a liquid is called solute. It is in smaller quan ty. The liquid that dissolves
a solute is termed as solvent. It is in larger quan ty. A uniform or homogeneous mixture of the solute and
the solvent is called solu on.
Solute + Solvent Solu on
(solid) (liquid) (liquid)
smaller quan ty larger quan ty

For example, when we add some sugar to a glass of water and mix it well, then we get a uniform mixture
known as sugar solu on. Here, sugar is the solute and water is the solvent.
Some more examples to iden fy solute and solvent in a solu on are given below.
• A solu on of common salt and water in which common salt is solute and water is solvent.
• A solu on of sodium carbonate and water in which sodium carbonate in solute and water is
solvent.
• A solu on of copper sulphate and water in which copper sulphate is solute and water is solvent.
It is no ceable that water always acts as a solvent and o en termed as universal solvent.
Substances like salt and sugar dissolve readily in water and are said to be soluble in water. Substances like
sand and wood that do not dissolve in water are said to be insoluble in water. Only soluble substances
can form a solu on. However, there are certain condi ons on which the forma on of a solu on depends.
They are as follows.
• S rring: S rring the solu on increases the solubility of the solute in the solvent.
• Par cle size of the solute: If the par cle size of the solute is Solubility
small, the rate of forma on of a solu on is faster. However, if
The ability of a solute to dissolve
the solute has large par cles, then the forma on of solu on into a solvent is called solubility.
takes me.
• Temperature: Mostly the solubility of solids and liquids in water increases with increase in
temperature. But solubility of gases in water decreases with increase in temperature.
Let’s perform some ac vi es to understand the condi ons aff ec ng the forma on of a solu on.

Activity 4.7

Aim: To observe the eff ect of s rring on the forma on of a solu on
Materials required: 2 beakers, some water, some sugar, a spoon
Procedure
• Take two beakers and label them as A and B.
• Pour equal amount of water in each beaker.
• Add one teaspoon of sugar each in both the beakers.
• Do not s r the contents of beaker A.
• S r the contents of beaker B.

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