Chapter 3, Problem 76A

Interpretation Introduction

Interpretation:

The mass of mercury oxide is 28.4 g and the mass of oxygen is 2.0 g. The mass percent of mercury in mercury oxide needs to be determined.

Concept introduction:

For any compound, the mass percent of any element present in it can be calculated as follows:

$\%m=\frac{m_{element}}{m_{compound}}\times 100\%$

Answer to Problem 76A

92.96%

Explanation of Solution

According to given reaction, the reactant is mercury oxide and products are mercury and oxygen. The law of conservation of mass says that total mass of reactant will be equal to that of products after the completion of the reaction.

Therefore,

$m_{\text{mercury oxide}}=m_{\text{mercury}}+m_{\text{oxygen}}$

Putting the values,

$\begin{array}{l}28.4\text{ g}=m_{\text{mercury}}+2.0\text{ g}\\ m_{\text{mercury}}=28.4-2.0\\ =26.4\text{ g}\end{array}$

Now, the mass percent of mercury in mercury oxide will be:

$\%m_{mercury}=\frac{{\text{m}}_{\text{mercury}}}{{\text{m}}_{\text{mercury oxide}}}\times 100\%$

Putting the values,

$\begin{array}{l}\%m_{mercury}=\frac{\text{26}\text{.4 g}}{28.4\text{ g}}\times 100\%\\ =92.96\%\end{array}$

Conclusion

Thus, the mass percent of mercury is 92.96%.