Question

Chromium has four naturally occuring isotopes. Cr-50 (mass of 49.946 amu and 4.35% abundance):

Cr-52 (mass of 51.941 amu and 83.79% abundance); Cr-53 (mass of 52.941 amu and 9,50% abundance); and Cr-54 (mass of 53,939 amu and 2.36% adundance). Calculate the average atomic mass of chromium.

Answer 1

To calculate the average atomic mass of chromium, you'll use the formula:

Average atomic mass = (mass of isotope 1 × abundance of isotope 1) + (mass of isotope 2 × abundance of isotope 2) + ... + (mass of isotope n × abundance of isotope n)

Given the isotopes of chromium and their abundances:

Cr-50: mass = 49.946 amu, abundance = 4.35%

Cr-52: mass = 51.941 amu, abundance = 83.79%

Cr-53: mass = 52.941 amu, abundance = 9.50%

Cr-54: mass = 53.939 amu, abundance = 2.36%

Plug in the values and calculate:

Average atomic mass = (49.946 amu × 0.0435) + (51.941 amu × 0.8379) + (52.941 amu × 0.0950) + (53.939 amu × 0.0236)

Average atomic mass = 2.172057 amu + 43.562999 amu + 5.01895 amu + 1.2686204 amu

Average atomic mass = 52.0226264 amu

So, the average atomic mass of chromium is approximately 52.02 amu.