Question

Copper has two isotopes: Cu-63, and Cu-65. The percent abundance of Cu-63 is

69.1%. What is the average atomic mass of copper? Assume the masses listed
are 63.000 and 65.000.

Answer 1

63.6 g/mol

Step-by-step explanation:

If the percent abundance of Cu-63 is 69.1%, then Cu-65 is 30.1% since

100%-69.1%= 30.1%

To find the average atomic mass, multiiply the percentage with the corresponding mass then add the answers together.

(63 x 69.1%) + (65 x 30.1%) = average atomic mass

(63 x .691) + (65 x .301) = 43.533 + 20.085 = 63.618 g/mol = 63.6 g/mol