The relative abundance of various isotopes of silicon is as Si (28) = 92.25%, Si (29) = 4.65% and Si (30) = 3.10%. Calculate the average atomic mass of silicon.

Explanation

To calculate the average atomic mass of silicon based on the relative abundance of its isotopes, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the isotopes and their relative abundances**:
- Silicon-28 (Si-28): 92.25%
- Silicon-29 (Si-29): 4.65%
- Silicon-30 (Si-30): 3.10%

2. **Convert the percentages to decimal form**:
- Si-28: \( \frac{92.25}{100} = 0.9225 \)
- Si-29: \( \frac{4.65}{100} = 0.0465 \)
- Si-30: \( \frac{3.10}{100} = 0.0310 \)

3. **Multiply the atomic mass of each isotope by its relative abundance**:
- For Si-28: \( 28 \times 0.9225 = 25.845 \)
- For Si-29: \( 29 \times 0.0465 = 1.3485 \)
- For Si-30: \( 30 \times 0.0310 = 0.930 \)

4. **Sum the results from step 3**:
- Total = \( 25.845 + 1.3485 + 0.930 = 28.1235 \)

5. **Round to an appropriate number of significant figures**:
- The average atomic mass of silicon is approximately \( 28.12 \, \text{g/mol} \).

### Final Answer:
The average atomic mass of silicon is **28.12 g/mol**.

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