Chapter 14, Problem 62A

Interpretation Introduction

Interpretation:

The difference between percent by mass and percent by volume has to be explained.

Concept Introduction:

The composition of a solution can be defined by expressing its concentration. The concentrations of solutions can be expressed in different ways, which are involved in the quantity of solute and the quantity of solution or solvent. Various methods are used to describe the concentration of the solution quantitatively. Some commonly used quantitative concentration terms are percent by mass, percent by volume, molarity, molality and mole fraction.

Mass percentage or percent by mass (w/W percent): Percent by mass equals the mass of the solute divided by the mass of the whole solution, multiplied by 100. The mass percentage of a component is defined as:

  $\mathrm{Mass}\hspace{0.17em}\%\hspace{0.17em}of\hspace{0.17em}a\hspace{0.17em}component=\frac{Mass of the component in the solution}{Total mass of the solution}\times 100$

Volume/volume percentage (v/V percent): Percent by volume is expressed as the ratio of the volume of the solute to the total volume of the solution multiplied by 100. The volume percentage of a component of a solution is defined as:

  $\mathrm{Volume}\hspace{0.17em}percentage\hspace{0.17em}\left(v/V\right)\hspace{0.17em}\%\hspace{0.17em}of\hspace{0.17em}a\hspace{0.17em}component=\frac{Volumeof the solute}{Total volume of the solution}\times 100$

Answer to Problem 62A

The percent by mass is a ratio between the mass of solute and the total mass of the solution, whereas percent by volume is a ratio between the volume of the solute and the total volume of the solution.

Explanation of Solution

Mass percentage or percent by mass (w/W percent): Percent by mass equals the mass of the solute divided by the mass of the whole solution, multiplied by 100. The mass percentage of a component of a solution is defined as:

  $\mathrm{Mass}\hspace{0.17em}\%\hspace{0.17em}of\hspace{0.17em}a\hspace{0.17em}component=\frac{Mass of the component in the solution}{Total mass of the solution}\times 100$

Volume/volume percentage (v/V percent): Percent by volume is expressed as the ratio of the volume of the solute to the total volume of the solution multiplied by 100. The volume percentage of a component of a solution is defined as:

  $\mathrm{Volume}\hspace{0.17em}percentage\hspace{0.17em}\left(v/V\right)\hspace{0.17em}\%\hspace{0.17em}of\hspace{0.17em}a\hspace{0.17em}component=\frac{Volumeof the solute}{Total volume of the solution}\times 100$