Question

The natural abundance for boron isotopes is 19.9% 10B and 80.1% 11B. Calculate boron's atomic mass and show work completely.

Answer 1

To determine the atomic mass of boron, convert the natural abundances to decimals and multiply each by the respective isotope mass. Summing these products gives the atomic mass, which is approximately 10.8 amu.

Step-by-step explanation:

To calculate the atomic mass of boron using its natural isotope abundances, we will use the isotopes B-10 with a mass of 10 amu and B-11 with a mass of 11 amu, as well as their abundances of 19.9% and 80.1% respectively.

The calculation is as follows:

1. Convert the percentages to decimal form by dividing them by 100. For B-10, it is 0.199 (19.9% / 100) and for B-11, it is 0.801 (80.1% / 100).
   
2. Multiply each isotope's mass by its respective decimal abundance: B-10: 10 amu × 0.199 = 1.99 amu, B-11: 11 amu × 0.801 = 8.811 amu.
   
3. Add these values together to get the atomic mass of boron: 1.99 amu + 8.811 amu = 10.801 amu, which is rounded to 10.8 amu.

Therefore, the atomic mass of boron is approximately 10.8 amu.