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In a periodic table, the averge atomic m...

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.

Text Solution

Verified by Experts

Let the abundance of `._(12)Mg^(25)` by mass be `x%`. Therefore, abundance of `._(12)Mg^(26)` by mass
`=(100-78.99-x)%=(21.01-x)%`
Now, average atomic mass of magnesium is :
`24.312=(23.98504xx78.99+24.98584x+25.98259(21.01-x))/100`
on solving, we get `x=9.303%` for `._(12)Mg^(25)` and for `._(12)Mg^(26), (21.01-x)=11.71%`
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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.

Average atomic mass of magnesium is 24.31 amu. This magnesium is composed of 79 mole % of 24mg and remaining 21 mole % of 25mg and 25mg . Calculate mole % of 26mg .

Knowledge Check

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  • Assertion: The average mass of one Mg atom is 24.305 amu , which is not actual mass of one Mg atom. Reason: Three isotopes, 24 Mg, 25 Mg and 26 Mg , of Mg are found in nature.

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