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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.
Interpretation:
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.
Comment:
- 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.
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