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3 years ago

Can anyone help ASAP!!

Chemistry

1 answer:

Sliva [168]3 years ago

4 0

The formula to determine the average atomic mass is:

Average atomic mass = $mass of the isotope 1 \times natural abundance of isotope 1$ + $mass of the isotope 2 \times natural abundance of isotope 2$ + ........ $+ mass of the isotope n \times natural abundance of isotope n$ -(1)

The atomic mass of first isotope of magnesium = 24 u (given)

The natural abundance of first isotope = 78.70 % (given)

The atomic mass of second isotope of magnesium = 25 u (given)

The natural abundance of first isotope = 10.13 % (given)

The atomic mass of third isotope of magnesium = 26 u (given)

The natural abundance of first isotope = 11.17 % (given)

Substituting the values in formula (1):

atomic weight = $(24 \times 0.7870) + (25 \times 0.1013) + (26 \times 0.1117)$

atomic weight = $24.4625 u$

Hence, the atomic weight of naturally occurring isotopic mixture is $24.4625 u$ .

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