Solutions are homogeneous mixtures of two or more pure substances.
A homogeneous mixture is a physical combination of two or more pure substances whose distribution throughout the mixture is uniform. What this means is that if we were to make a solution and take only a portion of the solution at random called an aliquot, the proportion of each pure substance in the aliquot would be the same as the proportion of that pure substance in the whole solution. We call these proportions to the whole solution the concentration . We are going to restrict our focus on this topic to two component solution systems with the minor component called the solute, and the major component called the solvent. Furthermore, we will restrict most of our comments to aqueous solutions where water is the solvent.