Question

What is the average atomic mass of Si if 92.21% of its atoms have mass 28 amu,

4.70% of its atoms have mass 29 amu, and 3.09% of its atoms have mass 30
amu?

Answer 1

The average atomic mass of Si is calculated by multiplying the mass of each isotope by its abundance percentage, resulting in 28.1088 amu.

Step-by-step explanation:

The average atomic mass of Si can be calculated using the given abundances and atomic masses of its isotopes. The average atomic mass is found by multiplying the mass of each isotope by its corresponding abundance (expressed as a fraction), and then summing these products.

• (92.21% of 28 amu) = 0.9221 × 28 = 25.8188 amu
• (4.70% of 29 amu) = 0.0470 × 29 = 1.3630 amu
• (3.09% of 30 amu) = 0.0309 × 30 = 0.9270 amu

Adding these values together:

25.8188 amu + 1.3630 amu + 0.9270 amu = 28.1088 amu

Therefore, the average atomic mass of Si is 28.1088 amu.