Solution and Suspension

Definitions

Solute is a substance which dissolves in a liquid is called a solute

A liquid which dissolves other substances is called a solvent

A solute dissolves in a solvent to give a solution

Therefore,

Solute + Solvent ----------> Solution

IMPORTANT

30cm3 of solute + 40cm3 of solvent ≠ 70cm3 of solvent

How is a solution formed?

When a solute dissolves in a solvent, the solute particles surround each solvent particles. The particles then intermix uniformly to form the solution. The solute and solvent particles do not combine chemically.

Types of solution

• Solid-liquid solution

• Gas-liquid solution

• Solid-solid solution

• Liquid-liquid solution

• Gas-gas solution

Suspension

When a solid does not dissolve in a liquid, a suspension is formed. The solid is said to be insoluble

A suspension is a mixture of small insoluble particles in a liquid or gas.

For all solutions, there is a limit to the amount of solute that can be dissolved in a given amount of solvent at a given temperature. The limit depends on the solubility of the solute.

A saturated solution contains the maximum amount of solute that can dissolve in a fixed amount of solvent at a particular temperature.

The solubility of a solute is the maximum amount of solute that can dissolve in 100g of solvent at a given temperature.

The higher the solubility, the more soluble the substance

The strength of a solution is referred to as concentration

The concentration of a solution is the amount of solute in 1dm3 of solution

1dm3 = 1000cm3

A concentrated solution contains more solute particles in a fixed amount of solvent than a dilute solution

A concentrated solution can be made more diluted by adding more solvent

To make a dilute solution more concentrated, we can add more solute or remove solvent by evaporating the solvent.

Factors that affect the extent of dissolving

Nature of solvent

The solubility of a solute is different in different solvent

Nature of solute

Different solute have different solubility in a solvent

Temperature

The higher the temperature of the solvent, the higher the solubility of the solute

Factors that affect rate of dissolving

Temperature

Most solute dissolve faster at higher temperature

Rate of stirring.

Solute dissolve faster when the solution is stirred

Size of solute particles

The larger the surface area, the faster the rate of dissolving as smaller piece solute have a larger surface area in contact with the solvent than compared to the larger pieces of solute