Respuesta :
Average atomic mass of an element is the sum of atomic mass of its isotopes multiplied by their respective percentage abundance.
There are four isotopes of element X:
1. 4.350 % with mass 49.94605 amu
2. 83.79% with mass 51.94051 amu
3. 9.5% with mass 52.94065 amu
4. 2.360% with mass 53.93888 amu
Thus, average atomic mass will be:
[tex]=49.94605(\frac{4.350}{100})+51.94051(\frac{83.79}{100})+52.95065(\frac{9.5}{100})+53.93888(\frac{2.360}{100})[/tex]
Or,
[tex]Average atomic mass=2.173 amu+43.52 amu+5.029 amu+1.273 amu=51.99 amu[/tex]
Therefore, average atomic mass of element X will be 51.99 amu (four significant figures)
Answer: 52.00 amu.
Explanation:
Mass of isotope 1 = 49.94605 amu
% abundance of isotope 1 = 4.350% = [tex]\frac{4.350}{100}=0.0435[/tex]
Mass of isotope 2 = 51.94051 amu
% abundance of isotope 2 = 83.79 % = [tex]\frac{83.79}{100}=0.8379[/tex]
Mass of isotope 3 = 52.94065 amu
% abundance of isotope 3 = 9.500 % = [tex]\frac{9.500}{100}=0.095[/tex]
Mass of isotope 4 = 53.93888 amu
% abundance of isotope 4 = 2.360 % = [tex]\frac{2.360}{100}=0.0236[/tex]
Formula used for average atomic mass of an element :
[tex]\text{ Average atomic mass of an element}=\sum(\text{atomic mass of an isotopes}\times {{\text { fractional abundance}})[/tex]
[tex]A=\sum[(49.94605\times 0.0435)+(51.94051\times 0.8379)+(52.94065\times 0.095)+(53.93888\times 0.0236)][/tex]
[tex]A=52.00amu[/tex]
Therefore, the average atomic mass of an element is 52.00 amu.
