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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 butane


1) Complete combustion of butane

The gas inside of a lighter is butane therefore the ignition of a lighter provides a simple mean to study combustion of butane.

To analyze this combustion some tests are realized:

- If a lighter flame is put in a test tube, its walls are covered with condensation. We can verify that this condensation is made of water using anhydrous copper sulfate ( it should turn blue ).
Combustion continues a few moments and then the flame goes out.

- The test tube is then used to collect gases produced during the combustion. In this tube the lime water test is positive.

The combustion therefore produces water and carbon dioxide and It consumes dioxygen and butane.

Reactants are butane and oxygen
Products are carbon dioxide and water

Chemical reaction::
                     Butane + dioxygen   →      carbon dioxide + water

It is said that such combustion is complete combustion.


2) Incomplete combustion of butane

If there is not enough dioxygen to burn all the butane then combustion is incomplete:
In addition to other products it appears a black solid compound ( carbon ) and a gaseous compound colorless, odorless and very toxic ( carbon monoxide )

Chemical reaction is then :
Butane + dioxygen     →    carbon dioxide + water + carbon + carbon monoxide

Comment: butane as well as methane, ethane and propane are natural gases. They burn producing water and carbon dioxide, moreover these combustions may also be incomplete.