Chapter 3, Problem 74A

Interpretation Introduction

Interpretation:

The mass of the unknown sample of compound is 25.3 g. The mass of oxygen present in it is 0.8 g. The mass percent of oxygen 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 74A

3.16%.

Explanation of Solution

The mass of the unknown compound is 25.3 g and the mass of oxygen present in it is 0.8 g.

The mass percent of oxygen in the compound can be calculated as follows:

$\%m_O=\frac{m_O}{m_{compound}}\times 100\%$

Putting the values,

$\begin{array}{l}\%m_H=\frac{0.8\text{ g}}{25.3\text{ g}}\times 100\%\\ =3.16\%\end{array}$

Conclusion

Thus, the mass percent of O is 3.16%.