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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



The combustion of carbon


1) Description of the combustion of carbon

Carbon is a substance existing under various forms but the one that may most easily burn is the charcoal (also used in drawing).

- Step 1: initiating combustion.
The initiation allows the combustion to start.
The charcoal is placed in a flame until it becomes hot enough to emit a red light: the charcoal is then incandescent.

- Step 2: Combustion of charcoal in the air
The charcoal is removed from the flame.
Charcoal still burns in the air and remains incandescent.

- Step 3: Combustion of charcoal in the pure dioxygen.
The incandescent charcoal is placed in a container initially containing pure dioxygen.
When the incandescent fusain is placed in the container, a flame forms and some sparks are projected.
Combustion is more intense in pure dioxygen than in air.

- Step 4: End of combustion
After a few moment the combustion becomes less and less intense and  then stops.
A part of the fusain has disappeared during combustion.

- Step 5: Analysis of the content of the container where furcoal has burnt.
The limewater test is positive and indicates the presence of carbon dioxide



2) Interpretation of the combustion of carbon

- Combustion is stronger in pure dioxygen (100% dioxygen) than in air (21% dioxygen):dioxygen is required for combustion of charcoal.

- In pure dioxygen combustion stops even if charcoal hasn't totally disappeared. It means that another compound lacks: dioxygen.
Combustion of charcoal consumes dioxygen.

- A part of charcoal (composed of carbon) has disappeared during combustion:
This combustion consumes carbon

-Limewater test indicates the presence of carbon dioxide( limewater turns cloudy): Carbon dioxide has formed during this combustion

- Conclusion:
The combustion of charcoal in dioxygen is a chemical transformation during which some compounds disappear (carbon and dioxygen) and another compound appears (carbon dioxide).