Chapter 6, Problem 66A

Interpretation Introduction

Interpretation: The empirical formula of binary compound formed needs to be determined when barium metal is heated with chlorine gas.

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 66A

The empirical formula must be ${\text{BaCl}}_{\text{2}}$ .

Explanation of Solution

Given information:

• Ba = 65.95 %
• Cl = 34.05 %

Calculate moles of each with the help of atomic mass:

Consider mass percentage as mass of element to make 100 g of compound.

  $\begin{array}{l}\text{Ba = }\frac{\text{65}\text{.95 g}}{\text{137}\text{.0 g/mol }}\text{=0}\text{.481 moles}\\ \text{Cl = }\frac{\text{34}\text{.05 g}}{\text{35}\text{.5 g/mol }}\text{= 0}\text{.959 moles}\end{array}$

Divide by least moles to get the whole number ratio:

  $\begin{array}{l}\text{Ba = }\frac{\text{0}\text{.481 }}{\text{0}\text{.481}}\text{= }1\\ \text{Cl = }\frac{\text{0}\text{.959}}{\text{0}\text{.481}}\text{= 1}\text{.99}\approx \text{2}\end{array}$

Thus the empirical formula must be ${\text{BaCl}}_{\text{2}}$ .

Conclusion

The empirical formula must be ${\text{BaCl}}_{\text{2}}$ .