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Naturally occurring silicon consists of three isotopes with the following isotopic masses and abundances. IsotopeIsotopic mass (u)Abundance (%) 28 Si 27.9769265327 92.2297 29 Si 28.97649472 4.6832 30 Si 29.97377022 3.0872 Calculate the average atomic mass of naturally occurring silicon to at least four significant figures.

Answer :

Answer: The average atomic mass  of naturally occurring silicon  is 28.08

Explanation:

Mass of isotope Si-28 = 27.9769265327

% abundance of isotope Si-28 = 92.2297% = [tex]\frac{92.2297}{100}[/tex]

Mass of isotope Si-29 = 28.97649472

% abundance of isotope Si-29 = (4.6932)% = [tex]\frac{4.6832}{100}[/tex]

Mass of isotope Si-30 = 29.97377022

% abundance of isotope Si-30 = (3.0872)% = [tex]\frac{3.0872}{100}[/tex]

Formula used for average atomic mass of an element :

[tex]A=\sum[(27.9769265327\times \frac{92.2297}{100})+(28.97649472\times \frac{4.6832}{100})+(29.97377022\times \frac{3.0872}{100})][/tex]

[tex]A=28.08[/tex]

Therefore, the average atomic mass  of naturally occurring silicon  is 28.08