Question

what is the atomic mass of silicon if 92.21% of its atoms have a mass of 27.977 amu, 4.700% have a mass of 28.976 amu, and 3.090% have a mass of 29.974 amu? round your answer to four significant digits and only include the number without the units for the answer. assume the units to be in amu.

Explanation:

Step1: Convert percentages to decimals

$92.21\% = 0.9221$, $4.700\%=0.04700$, $3.090\% = 0.03090$

Step2: Calculate the weighted - average

$m = 0.9221\times27.977+0.04700\times28.976 + 0.03090\times29.974$
$m=0.9221\times27.977+0.04700\times28.976+0.03090\times29.974$
$=25.8939917+1.361872+0.9261966$
$=28.1820603$

Step3: Round to four significant digits

$28.18$

Answer:

$28.18$