Question

Boron has two naturally-ocurring isotopes. Boron-10 has an abundance of 19.8% and actual mass of 10.013 amu, and boron-11 has an abundance of 80.2% and actual mass of 11.009 amu. What is the average atomic mass for all isotopes of boron?

Answer 1

10.812 to the nearest thousandth,.

Step-by-step explanation:

That would be 0.198 * 10.013 + 0.802 * 11.009

= 10.812.

Answer 2

Average atomic mass = 10.812 amu

Step-by-step explanation:

The formula for the calculation of the average atomic mass is:

`Average\ atomic\ mass=(\frac {\%\ of\ the\ first\ isotope}{100}* {Mass\ of\ the\ first\ isotope})+(\frac {\%\ of\ the\ second\ isotope}{100}* {Mass\ of\ the\ second\ isotope})`

Given that:

For first isotope, Boron-10:

% = 19.8 %

Mass = 10.013 amu

For second isotope, Boron-11:

% = 80.2 %

Mass = 11.009 amu

Thus,

`Average\ atomic\ mass=(19.8)/(100)* {10.013}+(80.2)/(100)* {11.009}=1.982574+8.829218=10.811792`

Average atomic mass = 10.812 amu