Home
Class 12
PHYSICS
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 `" "_(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.

Text Solution

Verified by Experts

It is given that abundance of `" "_(12)^(24)Mg` (23.98504 u) is 78.99%. Let abundance of `" "_(12)^(26)Mg` (25.98259 u) be x%. Then abundance of `" "_(12)^(25)Mg` (24.98584 u) will be `[100 - (78.99 + x)]% or (21.01 - x)%`.
`therefore` Average atomic mass `24.312=(23.98504 xx 78.99 + 24.98584 (21.01 - x) + 25.98259 (x))/100 implies 2431.2 = 1894.5783 + 524.9525 + 1.0006 x implies x= (2431.2 - 1894.58 -524.95)/1.0006=11.7 %`.
Hence, the abundance of `" "_(12)^(26)Mg` is 11.70% and that of `" "_(12)^(25)Mg` is (21.01 - 11.70) =9.3%.
Promotional Banner

Topper's Solved these Questions

  • NUCLEI

    U-LIKE SERIES|Exercise CBSE Based/Source -Based Integrated Questions|3 Videos

  • NUCLEI

    U-LIKE SERIES|Exercise Multiple Choice Questions|30 Videos

  • NUCLEI

    U-LIKE SERIES|Exercise Self Assessment Test|10 Videos

  • MOVING CHARGES AND MAGNETISM

    U-LIKE SERIES|Exercise SELF ASSESSMENT TEST (SECTION D)|1 Videos

  • RAY OPTICS AND OPTICAL INSTRUMENTS

    U-LIKE SERIES|Exercise SELF ASSESSMENT TEST (SECTION B)|3 Videos

Similar Questions

Explore conceptually related problems

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.

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 .

Boron has two isotopes, B-10 and B-11. The average atomic mass of boron is found to be 10.80u. Calculate the percentage of abundance of these isotopes.

Carbon found nature as a mixture of C-12 and C-13. The average atomic mass of carbon is 12.011u. What is the percentage abundance of carbon-12 in nature ?

Average atomic mass of magnesium is 24.31 amu. This magnesium is composed of 79 mole % of .^(24)Mg and reamainig 21 mol % of .^(25)Mg and .^(26)Mg . Calculate mole % of .^(26)Mg .

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 :-

Calculate the average atomic mass of hydrogen using the following data Isotope % Natural abundance Molar mass .^(1)H 99.985 1 .^(2)H 0.015 2

An element is found in nature in two isotopic forms with mass numbers (A-1) and (A+3). If the average atomic mass of the element is found to be A, then the relative abundance of the heavier isotope in the nature will be :