Question

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 1

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

Step-by-step explanation:

Mass of isotope Si-28 = 27.9769265327

% abundance of isotope Si-28 = 92.2297% =
`(92.2297)/(100)`

Mass of isotope Si-29 = 28.97649472

% abundance of isotope Si-29 = (4.6932)% =
`(4.6832)/(100)`

Mass of isotope Si-30 = 29.97377022

% abundance of isotope Si-30 = (3.0872)% =
`(3.0872)/(100)`

Formula used for average atomic mass of an element :

`A=\sum[(27.9769265327* (92.2297)/(100))+(28.97649472* (4.6832)/(100))+(29.97377022* (3.0872)/(100))]`

`A=28.08`

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