Question

Copper has two isotopes copper-63 has an atomic mass of 62.9296u

Answer 1

Answer:

- 63 and Cu - 65. The mass of Cu - 63 is 62.9396 amu, and the mass of Cu - 65 is 64.9278 amu. Use the atomic mass of copper to determine the relative abundance of each isotope in a naturally occurring sample. Express your answers numerically separated by a comma.

Determining relative abundance of isotopes

For each element on the Periodic Table, the atomic mass given is actually the average atomic mass of all the element atoms in a natural sample. The atoms are distributed unevenly among all the element's isotopes, affecting the average atomic mass.

Answer and Explanation:

The average atomic mass of Cu is 63.54 amu, the mass of Cu - 63 is 62.9396 amu, and the mass of Cu - 65 is 64.9278 amu.

Let x = the percentage (out of 100) that is Cu-63, and let y = the percentage out of 100 that is Cu-65.

Then:

x + y = 100

62.9396x + 64.9278y = 6354 (63.54 x 100)

Solving for x:

x = 100 - y

(62.9396)(100-y) + 64.9278y = 6354

6293.96 - 62.9396y + 64.9278 y = 6354

1.9882 y = 60.04

y = 30.1982 % = the percentage of Cu-65

x = 100 - 30.1982 = 69.8018 % = % of Cu-63

Finally, round off the final answer to the correct number of significant figures: Cu-65 30.20%, Cu-63 69.80%

Explanation:

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