Question

What is the percent composition by mass of Sn and O in SnO2?

Answer 1

To find the percent composition by mass of each element in the compound SnO₂ (tin(IV) oxide), we need to calculate the molar mass of the compound and then determine the mass percent of each element.

1. **Calculate the molar mass of SnO₂:**
- The molar mass of tin (Sn) is approximately 118.71 g/mol.
- The molar mass of oxygen (O) is approximately 16.00 g/mol.

The formula for SnO₂ indicates that there is 1 tin atom and 2 oxygen atoms:
\[
\text{Molar mass of SnO}_2 = (1 \times 118.71 \, \text{g/mol}) + (2 \times 16.00 \, \text{g/mol})
\]

\[
= 118.71\, \text{g/mol} + 32.00\, \text{g/mol} = 150.71\, \text{g/mol}
\]

2. **Calculate the mass percent of Sn:**
\[
\text{Mass percent of Sn} = \left( \frac{\text{mass of Sn}}{\text{molar mass of SnO}_2} \right) \times 100
\]
\[
= \left( \frac{118.71\, \text{g/mol}}{150.71\, \text{g/mol}} \right) \times 100 \approx 78.7\%
\]

3. **Calculate the mass percent of O:**
\[
\text{Mass percent of O} = \left( \frac{\text{mass of O}}{\text{molar mass of SnO}_2} \right) \times 100
\]
\[
= \left( \frac{32.00\, \text{g/mol}}{150.71\, \text{g/mol}} \right) \times 100 \approx 21.3\%
\]

Thus, the percent composition by mass of Sn and O in SnO₂ is approximately:
- **Tin (Sn): 78.7%**
- **Oxygen (O): 21.3%**