Hello!
To find the average atomic mass of boron, we need to use this formula:
Average Mass = (mass of isotope #1)(percent abundance) + (mass of isotope #2)(percent abundance) + ...
Before we use the formula, we need to convert the percentages into decimals. Remember that all percentages are out of 100, so, we divide the percent by 100 to get it into decimal form.
19.8 / 100 = 0.198
80.2 / 100 = 0.802
Average Mass = (10.013 amu)(0.198) + (11.009 amu)(0.802)
Average Mass = 1.98 amu + 8.83 amu
Average Mass = 10.81 amu
Therefore, the average atomic mass of boron is 10.81 amu.
10.8 amu is the atomic mass of boron.
Given:
The two isotopes of boron (B).
Boron-10 has an abundance of 19.8% and Boron -11 has an abundance of 80.2%
To find:
The atomic mass of europium.
Solution:
Mass of Boron-10 = 10.013 amu
The percentage abundance of Boron-10 = 19.8%
The fractional abundance of Boron-10 =0.198
Mass of Boron-11 = 11.009 amu
The percentage abundance of Boron-11= 80.2%
The fractional abundance of Boron-11= 0.802
The average atomic mass of Boron = A.M
[tex]A.M=\Sum{\text{Mass of isotope }\times \text{Fractional abundance of isotope}}\\=10.013 amu\times 0.198+ 11.009 amu\times 0.802=10.81 u\approx 10.8amu[/tex]
10.8 amu is the atomic mass of boron.
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