Summary and Introduction
To be a solution, a mixture must be homogeneous--its components must be
uniformly dispersed
and separable only by chemical means. There are two parts of a solution,
the solvent and the
solutes. The solvent is what we call the major component and a solvent
is one of the minor
components. Solutions can be made between many phases of matter. For
example, salt water is a
solution of a solid solute (NaCl) in a liquid solvent (water) and air is a
solution of a variety of
gaseous solutes, including oxygen, in the gaseous solvent nitrogen.
To understand solutions we must first understand their compositions. To do
so, we need to develop
a quantitative way to talk about the concentration of a solution. Many different
units of concentration have
been developed. Mass percent is the mass of solute divided by the mass
of the solution.
Mole fraction is the number of moles of solute divided by the total
number of moles of solvent.
Molarity, perhaps the most common concentration unit, is the number of
moles of solute divided
by the number of liters of solution. Molality is the number of moles of
solute divided by the
number of kilograms of solvent. Normality is the number of molar
equivalents of solute
per liter of solution.
In addition to a discussion of the concentrations of solutions, we will
briefly touch upon the ways in
which solutions are made, including dilution.
