Question

Iron (Fe) has three isotopes. Calculate the average atomic mass of the element Fe using the following data: Isotope atomic mass (u) % abundance Fe-54 53.94 6% Fe-56 55.93 92% Fe-57 56.94 2%

Answer 1

Answer:

Average atomic mass = 55.83 amu

Explanation:

The formula for the calculation of the average atomic mass is:

$Average\ atomic\ mass=(\frac {\%\ of\ the\ first\ isotope}{100}\times {Mass\ of\ the\ first\ isotope})+(\frac {\%\ of\ the\ second\ isotope}{100}\times {Mass\ of\ the\ second\ isotope})+(\frac {\%\ of\ the\ third\ isotope}{100}\times {Mass\ of\ the\ third\ isotope})$

Given that:

For first isotope, Fe-54:

% = 6 %

Mass = 53.94 amu

For second isotope, Fe-56:

% = 92 %

Mass = 55.93 amu

For third isotope, Fe-57:

% = 2 %

Mass = 56.94 amu

Thus,  

$Average\ atomic\ mass=\frac{6}{100}\times {53.94}+\frac{92}{100}\times {55.93}+\frac{2}{100}\times {56.94}$

Average atomic mass = 55.83 amu