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Mixtures and solutions

Dissolving a solid in water

1) What is a dissolution ?

When a solid forms a homogeneous mixture with water it is said that:
- The solid dissolves in water.
- The solid is soluble in water.
Examples: salt, sugar, cocoa powder are soluble in water.

When a solid dissolves in water it is reduced to fine particles invisible to the naked eye which are dispersed in water.

The mixture obtained in a dissolution is called an aqueous solution.
The water used to dissolve the solid is called a solvent.
The solid which is dissolved is called a solute.

- There are non-aqueous solutions obtained with other solvents such as alcohol.
- The solids dissolved in water does not change state. These solids have just been reduced in particles that are too small to be seen with the naked eye.
2) Saturation of a solution

IThere is a limit to the amount of solid that can be dissolved in a volume of water.
When this limit is reached, we say that the solution is saturated.

As long as the saturation limit is not reached the solid added in water can be dissolved.
When the saturation limit is reached the solid no longer dissolves and remains visible.

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


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