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Free online chemistry lesson for elementary school, middle school and high school.
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Science class




Mechanics lessons
Water on Earth
Changes of state in the nature: the water cycle
Water in human body
Test for water
Properties of water in different states
States of matter
States of matter and its changes
Boiling water
Water: freezing and melting
Changes of state: mass and volume
Molecules in different states of matter

Mixtures and solutions
Heterogeneous mixtures
Homogeneous mixtures
Vaporization of water
Dissolving a solid in water
Conservation of mass on dissolving
Miscibility in water

Mass and volume
Volume and its units
Measuring volume with a graduated cylinder
Mass and its units
Measuring the mass of a liquid
Mass of a liter of water
Volumetric mass density
Air and atmosphere
Earth's atmosphere protect us
Threats to the Earth's atmosphere
Composition of air
Air and life
Atoms and molecules
Molecules in mixtures and pure substances
Molecules and states of matter
Composition of molecules
Constituents of the atoms
The electrical neutrality of the atom

Basics of combustion
The combustion of carbon
The combustion of butane
Atoms and chemical reactions
Chemical reactions
Chemical equations
Law of conservation of mass
Chemical synthesis

Most common metals

How to distinguish metals ?

Corrosion of metals

Electrical conductivity of solid materials

Electrons and free electrons

Electric current in metals
The conductivity of aqueous solutions
Aqueous solutions and ions
The direction of movement of ions
Formation of ions
Tests for ions
Acidic and basic solutions
pH of aqueous solutions
Ions in acidic and basic solutions
Dilution of acids and bases
Composition of hydrochloric acid
Chemical reaction between iron and hydrochloric acid

Electrochemical cells and chemical energy
Chemical reaction beteween a copper sulphate solution and zinc
Copper sulfate and zinc battery
Basics of electrochemical cell


Mixtures and solutions


1) How to realize a distillation ?

Distillation setup
Distillation setup 

- 1: This is the heating mantle used to heat the mixture to distill
- 2: This is the mixture to be distilled. It is heated to boiling.
- 3: This container is a flask.
- 4: The thermometer is used to control the temperature during the distillation.
- 5: The cooling water enters the condenser.
- 6: The cooling water leaves the condenser.
- 7: water condenser traversed by a cold water from a tap.
- 8: The liquid obtained by distillation is called a distillate.



2) Principle of distillation

The mixture placed in the flask is heated until boiling. The water it contains is then vaporized while the other compounds remain dissolved.
The water vapor passes through a condenser. Water vapor cools and liquefies to form droplets. Thes droplets flow and form the distillate.

All solid compounds initially dissolved in water, remain in the flask.
The distillate also called distilled water is formed of virtually pure water.

3) In which case can it be useful to realize a distillation ?

The vaporization can be used to recover the solid compounds dissolved in water nevertheless vaporized water is lost.
The main advantage of distillation is to obtain pure water.

There are more complex distillation techniques that allow separation of liquids.