CLASSIFYING MATTER

With matter, we distinguish between different types of substance by whether or not we can separate them using physical methods (for example: filtration, distillation or magnetic attraction):

· Pure substances: matter that cannot be separated into other substances using physical methods, for example, iron, oxygen or water.

· Mixtures: matter that can be separated into other substances using physical methods, for example, air, salt water or fizzy drinks.

So a mixture is a combination of two or more pure substances in which the identities of the original pure substances are maintained.

Mixtures can be:

· Heterogeneous mixtures: are those whose components we can see with the naked eye or with a microscope. Their composition and properties vary from one point of the mixture to another, for example, granite or water with oil.

· Homogeneous mixtures or solutions: are those whose components we can’t see with the naked eye or a microscope. They have the same composition and properties at every point, for example, water with sugar or air.

In this video you can learn how to prepare a solution in the laboratory.

A very special mixture: colloids

Colloidal dispersions are a special type of mixture (between a homogeneous and

heterogeneous mixture) in which the solute particles (invisible to the naked eye) are bigger than the particles in a solution (homogeneous mixture) but smaller than the particles in a heterogeneous mixture

You can see the difference between solution suspension and colloids in this video:

https://www.youtube-nocookie.com/embed/XEAiLm2zuvc?rel=0

Here is a web page where is explained what a colloid is.

https://www.priyamstudycentre.com/2021/03/colloid.html

You might observe this phenomenon when you see a car driving with the lights on in fog. The light from the headlamps spreads out in many directions because of the water drops in the air.

You might observe this phenomenon when you see a car driving with the lights on in fog. The light from the headlamps spreads out in many directions because of the water drops in the air.

It makes it easier to see the beams and even the water in the air.

This phenomenon is called the Tyndall effect and is caused by the fact that fog, just as the water in the cylinder on the right in the picture, is a colloidal dispersion.

In this video is explained: