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just olya [345]
3 years ago
8

An element has two naturally occurring isotopes, X-85 with a mass of 84.9118 amu and a natural abundance of 72.17%, and X-87 wit

h a mass of 86.9092 amu and a natural abundance of 27.83%. Calculate the atomic mass of this element.
Chemistry
1 answer:
QveST [7]3 years ago
5 0

Answer:

This element is Rubidium (Rb) and has an average atomic mass of 85.468 u

Explanation:

The average mass of an element is calculated by taking the average of the atomic masses of its stable isotopes.

The enitre atomic mass = 100 % or 1

⇒ this consists of X-85 with 72.17 % abundance  with atomic massof  84.9118 g/mol

72.17 % = 0.7217

⇒ this consists of X-87 with  27.83 % abundance with atomic mass of 86.9092 g/mol

27.83 % = 0.2783

To calculate the mass of this isotope we use the following:

0.7271 * 84.9118 + 0.2783 * 86.9092 =85.468 g/mol

This element is Rubidium(Rb) and has an average atomic mass of 85.468 u

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