16.2 Solution Concentration
16.2 Solution Concentration
Lesson Objectives
- Describe the concept of concentration as it applies to solutions, and explain how concentration can be increased
or decreased. - Define molarity and molality, including the most commonly used units for each measurement.
- Define weight percent and be able to determine the weight percent of a solute in a given solution.
- Understand how a dilution changes the concentration of a solution, and be able to perform calculations related
to this process.
Lesson Vocabulary
- molarity (M): Moles of solute per liter of solution (mol/L).
- molality (m): Moles of solute per kilogram of solvent (mol/kg).
- weight percent (w/w): The weight of solute divided by the weight of solution, expressed as a percentage.
- parts per million (ppm): The number of particles of a certain solute divided by the total number of particles
in a solution, converted to number of particles of solute per one million particles of solution. - dilution: The process of lowering the concentration of a solution by adding more solvent.
Check Your Understanding
- Which of the following statements is false regarding a solution?
a. The amount of solute is always less than the amount of solvent.
b. Water is a common solvent.
c. You can have a solution where there is zero solute.
d. Polar solutes will likely dissolve in polar solvents.Introduction
A solution is comprised of at least two components - the solvent and one or more solutes. Although many different
substances (including solids, liquids, and gases) can act as a solvent, we are now going to focus primarily on aqueous
solutions, in which water acts as the solvent. Water is the most common solvent that we encounter in our daily lives.
In this section, we will explain how to determine the concentration for a given solution and how to create solutions
of known concentrations.