Is matter around us pure? – Separation of Liquids


What are Immiscible and Miscible liquids?

● Immiscible liquids

Liquids that do not form a homogeneous mixture when mixed together are called Immiscible liquids. When these liquids are mixed, they form distinct layers.

For example, a mixture of oil and water.

● Miscible liquids

Liquids that mix together to form a homogeneous mixture are called Miscible liquids. For example, a mixture of water and ethanol.

Separation methods for liquids

● Separation Funnel

Immiscible liquids can be separated using a special apparatus called a separation funnel.

It is a cone-shaped instrument made from glass. It has a stopper at the top to close the mouth of the funnel. There is a tap or a stopcock at the bottom which controls the flow of the liquid.

To separate two immiscible liquids like oil and water, their mixture is poured into the funnel after taking care that the tap is closed. The stopper is placed on the top. Then, the funnel is shaken so that the two liquids mix and reach a state of equilibrium.

Separation funnel

Separation funnel

The funnel is then placed on a retort stand to place the funnel and allowed to rest. After some time, the two liquids formed two distinct layers.

Since the density of oil is lower than that of water, it forms a layer above the water. Opening the tap of the funnel, the water can slowly be allowed to move out. Once all the water is collected, the tap is closed. What remains in the funnel is oil.

● Distillation

This process is used to separate two miscible liquids. We will learn about it in detail in the next segment.