Question

The average atomic weight of an element, which has two naturally occurring isotopes, is 53.6. One of the isotopes has an atomic weight of 52.9 amu and constitutes 60.9% of the total isotopes. The other isotope has an abundance of 39.1%. The atomic weight of the second isotope is ________ amu.

Answer 1

The atomic weight of the second isotope is 54.69 amu.

Step-by-step explanation

Given

Average atomic weight = 53.6 amu

isotope 1 atomic weight = 52.9 amu, abundance = 60.9%

Isotope 2 atomic weight = ?, abundance = 39.1%

Required: The atomic weight of the second isotope

Solution

The other isotope constitute of 39.1%

To calculate the weight of isotope 2:

Average atomic weight = m1P1 + m2P2 where m is the mass or weight and P is the %abundance

53.6 amu = (52.9 amu x 0.609) + (X x 0.391)

53.6 amu = 32.2161 + 0.391x

53.6 - 32.2161 = 0.391x

x = 54.69