Chapter 6, Problem 42A

Interpretation Introduction

Interpretation: The empirical formula of the oxide needs to be determined.

Concept Introduction: The empirical formula is the simplest ratio of atoms of elements present in the compound. It does not tell about the actual number of atoms present in it. Some molecules have empirical formulas equal to their molecular formula.

Answer to Problem 42A

CuO.

Explanation of Solution

The mass of copper metal is 10.0 g and oxygen is 2.52 g.

From mass and molar mass, the number of moles of copper and oxygen can be calculated as follows:

  $n=\frac{m}{M}$

The molar mass of copper and oxygen is 63.546 g/mol and 15.99 g/mol respectively.

The number of moles can be calculated as follows:

  $\begin{array}{l}{n}_{Cu}=\frac{m}{M}=\frac{10\text{ g}}{63.546\text{ g/mol}}=0.157\text{ mol}\\ n_O=\frac{2.52\text{ g}}{15.99\text{ g/mol}}=0.157\text{ mol}\end{array}$

Thus, the ratio of the number of moles of Cu to O is 0.157:0.157 or 1:1.

The empirical formula of oxide will be CuO.

Conclusion

Therefore, the empirical formula will be CuO.