Question

"A sample of silicon has an average atomic mass of 28. 084amu. In the sample, there are three isotopic forms of silicon. About 92. 22% of silicon atoms are 27. 9769amu, which have the mass of 28Si; about 4. 68% are 28. 9764amu, which have the mass of 29Si, and the remaining isotope, 30Si, has a mass of 29. 9737amu. Calculate the percent isotopic composition of 30Si. "

Answer 1

To calculate the percent isotopic composition of 30Si, we need to determine what percentage of the silicon sample is made up of 30Si.

First, let's add up the percentages of 28Si and 29Si to find the percentage of other isotopes in the sample:

Percentage of other isotopes = 100% - Percentage of 28Si - Percentage of 29Si

Percentage of other isotopes = 100% - 92.22% - 4.68% = 3.1%

Therefore, 3.1% of the silicon sample is made up of isotopes other than 28Si and 29Si.

Now, let's calculate the percentage of 30Si by subtracting the percentage of other isotopes from 100%:

Percentage of 30Si = 100% - Percentage of other isotopes

Percentage of 30Si = 100% - 3.1% = 96.9%

Therefore, the percent isotopic composition of 30Si in the silicon sample is approximately 96.9%.