Chapter 18, Problem 127A

Interpretation Introduction

Interpretation: The percent by mass of water in barium bromide tetrahydrate is to be calculated.

Concept Introduction: The ratio of the mass of the solute to the mass of the solution multiplied by 100 gives the formula for mass percentage.

Answer to Problem 127A

The percent by mass of water in barium bromide tetrahydrate is 19.5%.

Explanation of Solution

The formula for barium bromide tetrahydrate is ${\text{BaBr}}_{\text{2}}{\text{.4H}}_{\text{2}}\text{O}$ .

Now, calculate the percent by mass of water in barium bromide tetrahydrate as:

  $\begin{array}{c}\text{Mass percent}\text{of}\text{water}\text{in}{\text{BaBr}}_{\text{2}}{\text{.4H}}_{\text{2}}\text{O}=\frac{\text{Mass}\text{of}\text{water}}{\text{Molar}\text{mass}\text{of}{\text{BaBr}}_{\text{2}}{\text{.4H}}_{\text{2}}\text{O}}\times 100\%\\ =\frac{4\times 18\text{g/mol}}{369.17\text{g/mol}}\times 100\%\\ \text{Mass percent}\text{of}\text{water}\text{in}{\text{BaBr}}_{\text{2}}{\text{.4H}}_{\text{2}}\text{O}=19.5\%\end{array}$