Chapter 6, Problem 68A

Interpretation Introduction

Interpretation: The element A in compound A₂O which contains 63.7% of A and 36.3 % of Oxygen needs to be determined.

Concept Introduction: The molecular mass of compound is the sum of atomic mass of all the atoms present in the given chemical compound. Here the molecular formula represents the exact number of all bonded atoms in the compound.

Whereas empirical formula can be defined as the simplest positive integer ratio of all bonded atoms in the compound.

Answer to Problem 68A

Element A with molar mass 14.0 g/mol is Nitrogen.

Explanation of Solution

Given information:

A = 63.7%

O = 36.3 %

Calculate moles of O:

  $\text{O = }\frac{\text{36}\text{.3 g}}{\text{16}\text{.0 g/mol }}\text{=2}\text{.269 moles}$

According to A₂O formula:

1 mole of O = 2 moles of A

Thus moles of A = $\text{2 ×2}\text{.269 = 4}\text{.538 moles}$

Calculate molar mass of A:

  $\begin{array}{l}\text{ 4}\text{.538 moles = }\frac{\text{63}\text{.7 g}}{\text{molar mass }}\\ \text{Molar mass = }\frac{\text{63}\text{.7 g}}{\text{4}\text{.538 moles}}\\ \text{Molar mass = 14}\text{.0 g/mol}\end{array}$

Element A with molar mass 14.0 g/mol is Nitrogen.

Conclusion

Element A with molar mass 14.0 g/mol is Nitrogen.