Unit 6: Matter
1.- Physical changes.
2.- Chemical changes
3.- Separating mixtures
1.- Physical changes
- Change in state.
- Change in shape.
- Change in
positition or texture.
- Types of physical
changes.
- Mass, volume and
density.
1.1 Change in state
- We can see water
in three states:
- Solid.- Example:
ice. The atoms are packed together.
- Liquid.- water we drink. The atoms move around each
other.
- Gas.- water when is heating. The atoms are opened
each other.
1.2 Change in shape
- When we cut the
wood, fold a piece of paper or break a glass.
1.3 Change in position or texture.
- Matter can
change its position without changing its properties.
- Matter can also
change its texture.
1.4.- Types of physical changes
- Reversible.-
They come back again. Example: chocolate and juice can be liquid. Then solid
freezing and liquid again when it is heating.
- Irreversible.-
They are permanent. Example: if we cut bread, we cannot put the slices
back again.
1.5.- Mass, volume and density
·
Mass.- It is the amount of matter in an object. We can
measure the mass in grams( g) and kilograms. ( Kg).
·
Volume.- It is the space an object occupies. We measure
volume in millimitres (ml) and litres (
l ).
·
Density.- It is calculated by dividing the mass of an object by
its volume.
2.- Chemical changes
- When we are
talking about chemical changes, we can find: combustion, oxidation and
fermentation.
2.1.- Combustion
- It is a chemical
reaction that produces energy on the form of heat and light.
- It happens when
oxygen rects with fuels such as wood, gas and oil. The process is called
burning.
- When the fuels
are burning constitute new substances such as ash and smoke.
2.2.- Oxidation
- It is produced
when some metals react with the air.
- The atoms are
changed into a new substance.
- This substance
is called rust and it is brown. Then, the oxidation is produced.
2.3.- Fermetation
- Fermetation is
the chemical reaction in fungi and bacteria.
- During the
fermentation fungi produce alchohol and bacteria produce lactic. Oxigen does
not take part.
- Fermetation is
used to make food ( cheese and bread) and drinks( wine).
- Fermetation is
also used to preserve food such as vegetable, fruits and fish.
3.- Separating mixtures
- Magnetic separation
-
Decantation.
-
Filtration.
-
Evaporation.
-
Distilation.
3.0 Introduction
- There are two
types of mixtures: heterogeneous and homogeneous.
·
Heterogeneous.-
We can see the individual substances and they are easy to separate.
·
Homogeneous.-
We cannot see the individual substances and it is difficult to separate.
3.1.- Magnetic separation
- Magnets attract
certain types of metals.
- We can use
magnets for magnetic separations.
3.2.- Decantation
- Heavy sediments
in liquids are at the bottom.
- When we separate
the water and the heavy sediments, we are using decantation method.
- We can use
decantation as well with two liquids such as water and oil.
3.3.- Filtration
- Filtration
separate small particles from a liquid or gas.
- A filter is used
to catch the particles but allows the liquid to pass.
3.4.- Evaporation
- It is the process where a liquid is turning
into vapour.
- Evaporation
happens as well when the Sun heat the water of the rivers, oceans and seas.
3.5.- Distillation
- It is the
process where two liquids, such as water and ethanol, evaporate together but at
a different rate.
- We can divide
these two types of gas by the distillation process.
- Distillation is
used to produce alchohol.
