One way of separating chemicals is to use a ‘filter’. A face mask is a type of filter. It is made of material that is full of tiny holes. Air can pass through these holes but particles of dust or paint are too big and get trapped on the outside of the mask.
A filter cannot separate salt from a salt solution. The sodium and chlorine atoms and the water molecules which form a salt solution are small enough to pass through the holes of any filter. If the solution is warmed, the water begins to change into vapour and eventually only salt is left behind. We call this process ‘evaporation’. Stalagmites form by evaporation.
Chromatography
There are three primary colours — red, blue and yellow. Most inks are made by mixing two or more of these colours. To separate ink, a process called chromatography is used. To try this yourself, draw a small circle on blotting paper using a water-based pen. Then put a drop of water on top of the circle. As the water spreads through the blotting paper, it carries the chemicals at different speeds and separates the colours.
Electrolysis
Electrolysis is a process used to separate elements from compounds. An electrical current from a battery is passed through a liquid — called the electrolyte. Some molecules in the electrolyte are positively charged and others are negatively charged. Positively charged particles are attracted to the negative electrode. Negatively charged particles are attracted to the positive electrode. The liquid begins to separate. Electrolysis can be used to purify metals.
A Face mask separates chemicals by preventing large particles from passing through the holes.
Picture Credit : Google