Question

what is the average atomic mass of boron if it exists as 19.90% $^{10}$b (10.013 amu) and 80.18%? how to calculate average atomic mass? can we use the fraction directly? whats the product of fraction and mass number of 10 - b? whats the product of fraction and mass number of 11 - b? calculate the average atomic mass: feedback

Explanation:

Step1: Convert percentages to fractions

The fraction of $^{10}B$ is $0.1990$ and assume the mass of $^{11}B$ is $11.009$ amu (a common - known value) and its fraction is $0.8010$.

Step2: Calculate product for $^{10}B$

The product of the fraction and mass number of $^{10}B$ is $0.1990\times10.013 = 1.992587$.

Step3: Calculate product for $^{11}B$

The product of the fraction and mass number of $^{11}B$ is $0.8010\times11.009=8.818209$.

Step4: Calculate average atomic mass

The average atomic mass of boron is the sum of the above two products, $1.992587 + 8.818209=10.810796\approx10.81$ amu.

Answer:

$10.81$ amu