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Naturally occuring element Z is 78.99% of Z-24, 10% of Z-25 and 11.01% of Z-26. What is...

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lak-86 | Student, Undergraduate | Salutatorian

Posted June 30, 2013 at 6:39 AM via web

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Naturally occuring element Z is 78.99% of Z-24, 10% of Z-25 and 11.01% of Z-26. What is the relative mass of Z.

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llltkl | College Teacher | Valedictorian

Posted June 30, 2013 at 7:03 AM (Answer #1)

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Relative mass of an element is the weighted mean of the atomic masses of all the isotopes of the element, relative to 1/12 th of the mass of one C-12 isotope.

Relative Atomic Mass = [(mass of isotope 1)*(its % abundance) + (mass of isotope 2)*(its %  abundance) + (mass of isotope 3)*(its % abundance) + ... + (mass of isotope ’n’)*(its % abundance)]/100

For the naturally occurring element Z, it has three naturally occurring isotopes of mass 24, 25 and 26 a.m.u, with % abundances 78.99, 10 and 11.01 respectively.

Therefore, Relative Atomic Mass of element Z =(78.99*24+10*25+11.01*26)/100 = 24.3202

= 24.32 a.m.u. (approximately).

Sources:

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kavya--kammana | Student, Grade 12 | Valedictorian

Posted July 1, 2013 at 9:48 AM (Answer #2)

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relative mass of z = (.7899 * 24) + (.1 * 25) + (.1101 * 26) 

                          = 18.9576+

                               2.8626

                               2.5000

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                             24.3202..

                             

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