Mixtures are also referred to as Mechanical Mixtures
Mixtures can be heterogeneous or homogeneous.
Homogeneous mixtures show only one phase whereas heterogeneous mixtures show two or more phases.
A phase is a distinct portion of matter.
Examples: oil + water = heterogeneous, sand + charcoal powder = heterogeneous, sugar + water = homogeneous.
Oil droplets floating on the surface of water in a glass.
Solutions are Homogeneous Mixtures.
A colloid is a mechanical mixture in which the solute particles are so tiny that cannot be separated by gravity and remain suspended in the solvent.
A suspension is a mechanical mixture in which the particles of the solute are temporarily suspended in the solvent but can eventually settle out due to gravity.
Colloids show the Tyndall Effect.
Rays of light are refracted by dust particles suspended in the air showing the Tyndall Effect
A solution is a homogeneous mixture made up of two parts solvent and solute.
The solvent is the part of the solution that is doing the dissolving.
The solute is the part of the solution being dissolved.
Dissolving is a physical change that can be reversed.
The reversal of dissolving is precipitation or dehydration which can be obtained by evaporation.
Copper sulfate solution when dried on an evaporating dish will form crystals of solid copper sulfate, sea salt is obtained by salt sea water by evaporation.
A mixture of two solids (example: sand and salt ) is a mechanical mixture.
When two metals are liquefied (melted) and are mixed together, the resulting mixture is called an alloy.
For example brass is an alloy of coppermixed with tin in the liquid state and allowed to solidify.
Dentll fillings are a mechanical misxture of several metals called an amalgam.
Production of pure gold, for example is not commercially practical because it is too soft and expensive.
Alloys of gold contain different amounts of either copper or nickel to make it more durable.
Gold purity is measured in karats. 24-karat gold is 100% pure. 50% pure gold is 12-karat.