This document discusses different methods for separating mixtures and describes some common chemical reactions. It explains that mixtures can be either heterogeneous or homogeneous and various techniques like magnetic separation, decantation, filtration, evaporation and distillation can be used to separate substances in mixtures. It also provides examples of combustion, oxidation and fermentation as chemical reactions that result in new substances being formed.

2. Separating mixtures
and chemical reactions

3. Separating mixtures
• There are 2 types of mixtures:
heterogeneous – we can see the individual substances that
make it up
homogeneous – we can´t see the individual substances

4. We can separate substances in
mixtures in different ways:
Magnetic separation
Decantation
Filtration
Evaporation
Distillation

5. Magnetic separation
• We can use it if we want to
separate mixtures that consist of
substances attracted by magnets
and substances that are not

6. Decantation
• When we decant a liquid, we
pour off the liquid so that
sediment remains in the
container
• We can also use decantation
for two liquids of different
density (for example, oil and
water)
- heavy sediments in liquids sink to the bottom of a container

7. Filtration
• It is used for separating much
smaller particles from a liquid or
gas
• A filter is used to catch the
particles, but allows the liquid to
pass

8. Evaporation
• It is used to remove water in salt evaporation ponds
• Solids dissolved in a liquid can be separated using heat (the liquid
turns into vapour and the remaining sediment, the solids, can be
collected)

9. Distillation
• It is used to produce alcohol
and in the petrochemical industry
• we use distillation when two liquids
evaporate at a different rate (such
as water and ethanol)
• The liquid is heated (ethanol
evaporates first and forms vapour),
this vapour is then collected and
cooled, resulting in pure ethanol

10. Chemical reactions
• They change the properties of the original substance
• A new substance is created
Combustion
Oxidation
Fermentation

11. Combustion (burning)
• It is a chemical reaction that produces energy in the form of heat and
light
• It can happen when oxygen from the atmosphere reacts with a fuel
(for example wood, gas, oil…)
• when these fuels burn, the atoms in the substance react and form
new substances (such as ash and smoke)

12. Oxidation
• Some metals (for example, iron) react when they are exposed to air
and the atoms are changed into a new substance rust (it has
a brown colour)
• Oxidation also occures in some foods (apples, potatoes…)

13. Fermentation
• It is a chemical reaction where fungi or bacteria change organic
substances into other substances
• During fermentation, fungi produce alcohol and bacteria produce
lactic acid
• This chemical reaction is used to make cheese, bread, yoghurt, wine
and also to preserve food (fruit, vegetable, meat can be stored for
longer)