Previous Page: A Summary of Bond Types
In this module we are concerned with properties of solutions. Solutions are mixtures. Mixtures are two or more kinds of atoms that are mixed together but not chemically combined or changed in the process. Recall that the definition of compounds involves chemical change. With mixtures the atoms (or molecules) may be changed physically, or not at all.
Solutions are a special kind of mixture. Solutions are homogeneous. This means that if you examine a solution at any level, either at a distance (naked-eye) or close-up (microscope) any sample of the solution looks just like any other sample. Put a drop of cordial under a microscope. It still looks like a coloured liquid. Cordial is a solution. Put a drop of milk under a microscope. You can see the different bits - the solvent (water) the globs of milk fat. Milk is not a solution, though it is a mixture.
Terminology
Understanding the subject of solutions requires comprehension of a few technical terms.
For example
A teaspoon of table salt is poured into a glass of water and stirred until it dissolves. The table salt is soluble in water. Table salt is the solute, water is the solvent. The result is an unsaturated aqueous solution of table salt. Add more salt. Stir. Add more salt. Stir. Add more salt. Stir. Continue until after vigorous and prolonged stirring, visible crystals of salt still remain on the bottom of the glass. Now the solution is saturated. Place the glass in recently boiled water and stir. After all the salt has dissolved, cool it. If no salt precipitates out, you have a super-saturated solution.