Question

Weighted averages, help please

Answer 1

Answer:

Average atomic mass of Cl = 35.48 amu

Average atomic mass of B  = 10.8  amu

Average atomic mass of Ag  = 107.96 amu

Explanation:

1)

Given data:

Abundance of Cl-35 = 75.8%

Abundance of Cl-37 = 24.2%

Average atomic mass = ?

Solution:

Average atomic mass = (abundance of 1st isotope × its atomic mass) +(abundance of 2nd isotope × its atomic mass)  / 100

Average atomic mass  = (75.8×35)+(24.2×37) /100

Average atomic mass =  2653 + 895.4 / 100

Average atomic mass  = 3548.4 / 100

Average atomic mass  = 35.48 amu

2)

Given data:

Abundance of B-10 = 19.8%

Abundance of B-11 = 80.2%

Average atomic mass = ?

Solution:

Average atomic mass = (abundance of 1st isotope × its atomic mass) +(abundance of 2nd isotope × its atomic mass)  / 100

Average atomic mass  = (19.8×10)+(80.2×11) /100

Average atomic mass = 198  +882.2  / 100

Average atomic mass  = 1080.2 / 100

Average atomic mass  = 10.8  amu

3)

Given data:

Abundance of Ag-107 = 52%

Abundance of Ag-109 = 48%

Average atomic mass = ?

Solution:

Average atomic mass = (abundance of 1st isotope × its atomic mass) +(abundance of 2nd isotope × its atomic mass)  / 100

Average atomic mass  = (52×107)+(48×109) /100

Average atomic mass =  5564 +5232  / 100

Average atomic mass  = 10796 / 100

Average atomic mass  = 107.96 amu