Question

Silicon has three naturally occurring isotopes (Si-28, Si-29, and Si-30). The atomic mass and natural abundance of Si-28 are 27.9769 amu and 92.2 %, respectively. The atomic mass and natural abundance of Si-29 are 28.9765 amu and 4.67 %, respectively. Find the atomic mass of Si-30.

Answer 1

Answer:

The atomic mass of Si-30 is 29.955 amu

Explanation:

Step 1: Data given

Si-28 has an atomic mass of  27.9769 amu and a natural abundance of 92.2 %

Si-29 has an atomic mass of  28.9765 amu and a natural abundance of 4.67%

The atomic mass of Si is 28.0855 amu

Step 2: Calculate natural abundance of Si-30

100% - 92.2 % - 4.67% = 3.13 %

0.922 * 27.9769 + 0.0467 * 28.9765 + 0.0313* X = 28.0855

27.14790435 + 0.0313X = 28.0855

0.0313X = 0.93760

X = 29.955 amu

The atomic mass of Si-30 is 29.955 amu