Introduction
Homogenous mixtures have a uniform composition throughout e.g. salt water and sugar water, tincture alcohol [iodine+alcohol]. Solid solutions like alloys [brass = zinc + copper] and gaseous solutions like air are possible too.
Heterogeneous mixtures have non-uniform composition and physically distinct parts. e.g.: salt and iron filings, salt and sulfur.
Suspensions are solutions in which solutes don’t dissolve in the solvents but remain in suspension. e.g.: chalk powder in water.
Colloids: these are heterogeneous mixtures but the solutes are small in size they can’t be visible to the naked eye and so the mixture appears homogenous. Colloids can scatter beams of light passing through them i.e. Tyndall effect. Also, the particles of a colloid don’t settle if left undisturbed. e.g.: milk
Components of a colloid are:
Dispersed phase [solute-like] and Dispersing medium [solvent-like].
These can be separated by Centrifugation.
Dispersed Phase | Dispersing Medium | Type | Example |
Liquid | Gas | Aerosol | Fog, clouds, mist |
Solid | Gas | Aerosol | Smoke, automobile exaust |
Gas | Liquid | Foam | Shaving cream |
Liquid | Liquid | Emulsion | Milk, face cream |
Solid | Liquid | Sol | Milk of magnesia, mud |
Gas | Solid | Foam | Foam, rubber, sponge, pumice |
Liquid | Solid | Gel | Jelly, cheese, butter |
Solid | Solid | Solid Sol | Colored gemstone, milky glass |
Table 1: Examples of colloids
Chromatography is the process of separating solutes that dissolve in the same solvent. It’s also used for separating colors in the dye, pigments from natural colors, and drugs from the blood.
The separation of two miscible liquids that have sufficient differences in their boiling points can be done by distillation. If the difference is less than 25k then fractional distillation is done.
Miscellaneous facts:
Important Alloys:
a. Brass [copper + zinc]
b. Bronze [copper + tin],
c. Solder [lead + tin] welding electrical wires together.