Answer:
The atomic mass of phosphorus is 29.864 amu.
Explanation:
Given data:
Atomic mass of phosphorus = ?
Percent abundance of P-29 = 35.5%
percent abundance of P-30 = 42.6%
Percent abundance of P-31 = 21.9%
Solution:
Average atomic mass = (abundance of 1st isotope × its atomic mass) +(abundance of 2nd isotope × its atomic mass) + (abundance of 3rd isotope × its atomic mass / 100
Average atomic mass = (29×35.5)+(30×42.6) + (31×21.9) /100
Average atomic mass = 1029.5 + 1278 + 678.9/ 100
Average atomic mass = 2986.4 / 100
Average atomic mass = 29.864 amu.
The atomic mass of phosphorus is 29.864 amu.
Let's make ;
A = ounces solution A
B = ounces solution B
total number of ounces:
A + B = 120
concentration:
0.65A + 0.80B = 0.7(120)
Substitute A for 120 - B in the second equation to combine them.
0.65(120 - B) + 0.80B = 84
78 - 0.65B + 0.80B = 84
0.15B = 84 - 78
0.15B = 6
B = 6/0.15
B = 40 ounces
Then... A = 120 - 40
A = 60 ounces
