Mixtures and Solutions

In this lesson you can learn about mixtures and solutions.

Solute dissolving in a solvent and making the solution

What are mixtures and solutions?

Mixtures are kind of solutions. You can find many mixtures and solutions in your day-to-day life.

How is a solution made?

When a substance dissolves in a liquid a solution is made.

Seawater is a solution of salt and other substances in water.
Fizzy drinks contain the gas carbon dioxide dissolved in water.
Fish breathe oxygen that is dissolved in the water around them.
Liquids will dissolve in liquids (e.g. – Oil dissolves in petrol)
Solids will dissolve in solids (e.g. – Brass is made by dissolving copper metal in molten zinc metal)

Examples of soluble substances in water

Soap
Sugar
Salt
Milk powder
Washing- up liquid
Coffee granules
Soy sauce
Bath salt
Soluble Asprin

What is meant by ‘soluble’?

Soluble is the capability of being dissolved in a solvent.

When a substance is capable of being dissolved in a solvent, such as water that substance is a soluble substance.

What is meant by ‘insoluble’?

Insoluble is the incapability of being dissolved in a solvent.

When a substance is incapable of being dissolved in a solvent, such as water that substance is an insoluble substance.

What is a ‘solvent’?

Solvent is a liquid substance capable of dissolving other substances.

When a liquid dissolves a substance to form a solution it is a solvent.

e.g. – The best solvent in the world is water.

What is a ‘solute’?

The substance that dissolves in a solvent is called the ‘solute’.

What is a ‘solution’?

When a solute dissolves in a solvent, that mixture is called a ‘solution’.

Making Salt Solution

Making a Solution

If you put a teaspoon of salt in a glass of water, the salt seems to disappear and you have a salt solution.
If you put a teaspoon of sugar in a glass of water, the sugar seems to disappear and you have a sugar solution.

Particles

Making a sugar Solution

If you add a teaspoon of sugar to a glass of water, all the sugar will dissolve. How does this happen?

Water is made of very tiny particles. Sugar is made of slightly larger particles. Water particles have small spaces between them. They are close together and always moving. So if you add a teaspoon of sugar to a glass of water, the small moving water particles get between the larger sugar particles. Therefore we can see, sugar dissolves in water. Now you have a sugar solution.

Making a saturated sugar solution

If you add more and more sugar to a glass of water, eventually no more sugar will dissolve. How does this happen?

If you add more and more sugar to a glass of water, gradually the amount of water particles will decrease and the amount of sugar particles will increase. Eventually there will be no more water particles to get between the sugar particles. Now you have a saturated sugar solution.

What is a ‘saturated solution’?

A solution that contains all the dissolved substances it can hold is called a saturated solution. Some substances are very soluble. That means a lot of them dissolve in a certain amount of liquid. Some substances are slightly soluble.

Evaporating

What is meant by ‘evaporating’?

The changing of a liquid into a vapour is called evaporating.

Getting the dissolved sugar in the sugar solution back again

Heat the sugar solution on a saucer. Then the water in the sugar solution can evaporate away leaving the sugar on the saucer.

Evaporating Sugar Solution

Written By : K8School