Lesson 4: Solution Concentrations

One very important property of solutions that must be addressed is concentration. Concentration generally refers to the amount of solute contained in a certain amount of solution. To deal with concentration you must keep in mind the distinctions between solute, solvent and solution.

Because varying amounts of solute can be dissolved in a solution, concentration is a variable property and we often need to have a numerical way of indicating how concentrated a solution happens to be. Over the years a variety of ways have developed for calculating and expressing the concentration of solutions.

That can be done with percentages using measurements of weight (mass) or volume or both. It can also be done using measurements that more closely relate to ways that chemicals react with one another (moles).

In the pages that follow, several types of concentration will be presented. They include volume percent, weight percent, weight/volume percent, molarity (the workhorse of chemical concentrations), and normality (presented only briefly here - there will be more about it in another lesson).

You will get experience with more than one way of establishing the concentration of solutions. You can prepare a solution from scratch and measure each of the components that go into the solution. You can prepare a solution by diluting an existing solution. If an existing solution is colored, you can determine its concentration by measuring the intensity of color using colorimetry.