Chapter 8, Problem 102P

Interpretation Introduction

Interpretation:

The number of milligrams of ethanol present in $5\text{ L}$ of $0.08\text{ \%}$ (w/v) ethanol is to be calculated.

Concept introduction:

Several concentration units may be used to express the concentration. It is often useful to express the concentration in terms of percentage. This can be expressed as the amount of solute in grams dissolved in $100\text{ mL}$ of solution that is termed as weight by volume percentage. This is useful to express the concentration of solid solutes. The other way is to express the number of milliliters of solute per $100\text{ mL}$ of the solution. This is called the volume /volume percentage which is useful to express the concentrations of liquid solutes.

The formula to calculate the weight/volume percent concentration is as follows:

  $\text{Weight/volume percent}\left(\frac{\text{m}}{\text{v}}\right)\%=\frac{\text{Mass of solute}\left(\text{g}\right)}{\text{Volume of solution}\left(\text{mL}\right)}\times 100\%$

The conversion factor to convert milligrams to grams is as follows:

  $1\text{ mg}={\text{10}}^{-3}\text{ g}$

The conversion factor to convert $\text{L}$ to $\text{mL}$ is as follows:

  $\text{1L}=\text{1000 mL}$