Question

The average atomic mass of nickel is 58.693 amu. Given the data in the following table, what is the natural abundance of nickel-64?

⁵⁸Ni: 57.935 amu 68.0769% abundance

⁶⁰Ni: 59.931 amu 26.2231% abundance

⁶¹Ni: 60.931 amu 1.1399% abundance

⁶²Ni: 61.928 amu 3.6345% abundance

⁶⁴Ni: 63.928 amu ? % abundance

Answer 1

The average atomic mass of nickel is 58.693 amu.

To calculate the average atomic weight, each exact atomic weight is multiplied by its percent abundance (expressed as a decimal).

Let P be the abundance of Ni-64

So the resultant calculation is:

58.693= (57.935 x 0.680769) + (59.931 x 0.262231) + (60.931 x 0.011399) + (61.928 x 0.036345) + (63.928 x P)

58.693 = (39.440 + 15.715 + 0.69452 + 2.2507 + 63.929P)

58.693 = 58.100 + 63.929P

58.693-58.100 = 63.929P

0.593= 63.929P

P = 0.593/63.929 = 0.00927

so the natural percetage abundance of Ni-64 = 0.00927x100 = 0.927%