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In a periodic table, the average atomic ...

In a periodic table, the average atomic mass of magnesium is given as `24.312 u`. The average value is based on their relative natural abundance on earth. The three isotopes and their masses are `._12Mg^(24) (23.98504u)`, `._(12)Mg^(25) (24.98584)` and `._12Mg^(26) (25.98259 u)`. The natural abundance of `._12Mg^(24)` is `78.99%` by mass. Calculate the abundances of the other two isotopes.

Text Solution

Verified by Experts

Natural abundance of `""_(12)Mg^(24) = 78.99%`
Let natural abundance of `""_(12)Mg^(26)`
`=(100-(78.99 +x)) = (21.01-x)%`
As average atomic mass is calculated as weighted average of the masses of the isotopes
`therefore 24.312 u =(+(21.01-x)25.98259u)/100`
`rArr 0.99675x = 9.27`
`rArr x=9.27/0.99675 = 9.30%`
So `21.01 -x = 21.01-9.30 = 11.71`%
Hence relative abundance of `""_(12)Mg^(25) = 11.71`%
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In a periodic table, the averge atomic mass of magnesium is given as 24.312 u . The average value is based on their relative natural abundance on earth. The three isotopes and their masses are ._12Mg^(24) (23.98504u) , ._(12)Ng^(25) (24.98584) and ._12Mg^(26) (25.98259 u) . The natural abundance of ._12Mg^(24) is 78.99% by mass. Calculate the abundances of the other two isotopes.

In a periodic table, the average atomic mass of magnesium is given as 24,312 u. The average value is based on their relative natural abundance on earth. The three isotopes and their masses are " "_(12)^(24)Mg (23.98504 u), " "_(12)^(25)Mg (24.98584 u) and " "_(12)^(26)Mg (25.98259 u). The natural abundance of " "_(12)^(24)Mg is 78.99% by mass. Calculate the abundances of the other two isotopes.

Knowledge Check

  • boron has two isotopes B-10,B-11. The average atomic mass of boron is found to be 10.80u. Calculate the percentage abundance of B^(10) isotope :-

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    B
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