To determine the percent composition of silicon (Si) in silicon carbide (SiC), follow these steps:
1. Determine the atomic masses:
- The atomic mass of Silicon (Si) is 28.085 g/mol.
- The atomic mass of Carbon (C) is 12.011 g/mol.
2. Calculate the molar mass of silicon carbide (SiC):
- Silicon carbide consists of one atom of Silicon and one atom of Carbon.
- Therefore, the molar mass of SiC is the sum of the atomic masses of Si and C.
[tex]\[
\text{Molar mass of SiC} = 28.085 \, \text{g/mol (Si)} + 12.011 \, \text{g/mol (C)} = 40.096 \, \text{g/mol}
\][/tex]
3. Calculate the percent composition of Silicon in SiC:
- The percent composition is determined by the ratio of the atomic mass of Silicon to the molar mass of SiC, multiplied by 100.
[tex]\[
\text{Percent composition of Si} = \left( \frac{\text{Atomic mass of Si}}{\text{Molar mass of SiC}} \right) \times 100
\][/tex]
[tex]\[
\text{Percent composition of Si} = \left( \frac{28.085}{40.096} \right) \times 100 \approx 70.044 \%
\][/tex]
4. Select the closest option:
- Among the given options, the one closest to 70.044% is 70%.
Therefore, the correct answer is:
OC. 70%
