Copper occurs in an isotopic mixture of 69.09% ⁶³Cu (mass = 62.93 u per atom)and 30.91% ⁶⁵Cu (mass = 64.93 u per atom).What is the average atomic mass of copper? A)64.00 u B)63.55 u C)63.45 u D)64.31 u E)29.00 u

Question

Quizplus · Accepted Answer

To find the average atomic mass of copper, we need to calculate the weighted average of the two isotopes:

Average atomic mass = (% abundance isotope 1 x mass of isotope 1) + (% abundance isotope 2 x mass of isotope 2)

Plugging in the given values:

Average atomic mass = (0.6909 x 62.93 u) + (0.3091 x 64.93 u) = 63.55 u

Therefore, the correct answer is B.

Copper Occurs in an Isotopic Mixture of 69