Question

question 5. what is the atomic mass of silicon if 92.21% of its atoms have a mass of 27.977 amu, 4.70% have a mass of 28.976 amu, and 3.09% have a mass of 29.974 amu?

Explanation:

Step1: Convert percentages to decimals

$92.21\% = 0.9221$, $4.70\%=0.0470$, $3.09\% = 0.0309$

Step2: Calculate the contribution of each isotope

For the first isotope: $0.9221\times27.977$=$25.7098817$
For the second isotope: $0.0470\times28.976$ = $1.361872$
For the third isotope: $0.0309\times29.974$=$0.9261966$

Step3: Sum up the contributions

$25.7098817+1.361872 + 0.9261966=27.9979503\approx28.00$

Answer:

$28.00$ amu