Chapter 6.2, Problem 4RQ

Interpretation Introduction

Interpretation: The method to determine the mass percent of each element in water needs to be determined.

Concept Introduction: It is calculated as the mass of a component divided by the total mass of the total mass of the mixture, multiplied by 100%.

  $\text{Mass percentage of particular element=}\frac{\text{Mass of particular element}}{\text{Mass of compound}}\text{×100\%}$

Answer to Problem 4RQ

  $\text{Mass percentage of Hydrogen=11\%}$

  $\text{Mass percentage of Oxygen=88\%}$

Explanation of Solution

  ${\text{Molar mass of H}}_{\text{2}}\text{O=1×2+16=18g/mol}$

Mass contributed by oxygen = 16 g

Mass contributed by hydrogen = 2 g

  $\text{Mass percentage of particular element=}\frac{\text{Mass of particular element}}{\text{Mass of compound}}\text{×100\%}$

  $\text{Mass percentage of Hydrogen=}\frac{\text{Mass of Hydrogen}}{\text{Molar mass of water}}\text{×100\%}$

Putting the values,

  $\text{Mass percentage of Hydrogen}=\frac{2}{18}\times 100\%$

  $=0.11\times 100$

  $=11\%$

Now,

  $\text{Mass percentage of Oxygen=}\frac{\text{Mass of Oxygen}}{\text{Molar mass of water}}\text{×100\%}$

Also,

  $\text{Mass percentage of Oxygen=}\frac{\text{16}}{\text{18}}\text{×100\%}$

  $=0.88\times 100$

  $=88\%$