Answer:
221.37 u
Explanation:
The formula for the calculation of the average atomic mass is:
[tex]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})[/tex]
Given that:
For first isotope:
% = 65.51 %
Mass = 223.95 u
For second isotope:
Since the element has only 2 isotopes, so the percentage of second is 100 - first percentage.
% = 100 % - 65.51 % = 34.49 %
Let, Mass = x u
Given, Average Mass = 223.06 u
Thus,
[tex]223.06=\frac {65.51}{100}\times {223.95}+\frac {34.49}{100}\times {x}[/tex]
Solving for x, we get that:
x = 221.37 u
Thus mass of second isotope = 221.37 u