Chapter 13, Problem 5STP

Interpretation Introduction

Interpretation:

The percentage composition of elements in sodium hydroxide is to be calculated.

Concept introduction:

The percentage composition of a compound is relative mass of each component by mass in its 100 parts.

Answer to Problem 5STP

C

Explanation of Solution

$\begin{array}{c}MolecularmassofNaOH=22.9+16+1\\ =39.9\end{array}$

$\begin{array}{c}PercentageofNa=\frac{massofNa}{molecularmassofNaOH}\times 100\\ =\frac{22.9}{39.9}\times 100\\ =57.38\%\\ PercentageofO=\frac{massofO}{molecularmassofNaOH}\times 100\\ =\frac{16}{39.9}\times 100\\ =40.1\%\\ PercentageofH=\frac{massofH}{molecularmassofNaOH}\times 100\\ =\frac{1}{39.9}\times 100\\ =2.51\%\end{array}$

Conclusion

The mathematical calculations show that answer C is correct.