Question

Boron (B) has two naturally occurring isotopes: boron-10 (abundance = 19.8%, mass = 10.013 amu) and boron-11 (abundance = 80.2%, mass = 11.009 amu). Calculate the atomic mass of boron.

a. (10.013)(.198)+(11.009)(.802)=10.812
b. (10.013)(.198)+(11.009)(.802)=11.812
c. (10.013)(.802)+(11.009)(.198)=11.188
d. (10.013)(.802)+(11.009)(.198)=10.188

Answer 1

The atomic mass of boron is calculated by multiplying the mass of each isotope by its abundance and then adding the results. The correct calculation leads to an atomic mass of approximately 10.808 amu for boron.

Step-by-step explanation:

The atomic mass of boron can be calculated by taking into account the abundances and masses of its naturally occurring isotopes, boron-10 and boron-11. To find the atomic mass, we multiply the mass of each isotope by its respective abundance (expressed as a decimal), and then add the two values together. Using the provided data, we perform the calculation as follows:

Boron-10: Abundance = 19.8% or 0.198, Mass = 10.013 amu
Boron-11: Abundance = 80.2% or 0.802, Mass = 11.009 amu

The atomic mass of boron is therefore:
(10.013 amu × 0.198) + (11.009 amu × 0.802) = 1.982574 amu + 8.825218 amu = 10.807792 amu

After rounding to three decimal places, the atomic mass of boron is approximately 10.808 amu.