Chapter 16.2, Problem 21LC

Interpretation Introduction

Interpretation: The two ways in which the concentration of a solution as a percent is to be described.

Concept introduction: The concentration of the solution is defined as the amount of solute present in the given quantity of solution. There are different ways in which the concentration of the solution can be expressed and those are: molarity, molality, normality, percent by mass, and percent by volume. The most widely used concentration term is molarity.

Answer to Problem 21LC

The two ways to express the concentration of a solution in percent are percent by mass and percent by volume.

Explanation of Solution

Concentration of a solution can be expressed in percent by two methods such as:

• Percent by mass.
• Percent by volume.

The percent by mass is used for the system like solid in liquid which means in the system where the solute is solid and the solvent is liquid. The percent by mass can be defined as the ratio of the mass of the solute to the mass of the solution. The formula of percent by mass is as follows:

  $\text{Percent by mass = }\frac{\text{mass of solute}}{\text{mass of solution}}$

The other percent is the percent by volume by which a concentration of the solution is expressed. If the system is liquid in liquid that means, the solute and solvent both are liquid then, this is used. The percent by volume is defined as the ratio of the volume of a solute to the volume of the solution. The formula of percent by volume is as follows:

  $\text{Percent by volume = }\frac{\text{volume of solute}}{\text{volume of solution}}$

Conclusion

The two ways to express the concentration of a solution in percent are percent by mass and percent by volume.