Question

The atomic weight of a newly discovered e ement is 98.225 amu. It has two naturally occuring isotopes. One isotope has a mass of 96.780 amu. The second isotope has a percent abundance of 41.7%. What is the mass of the second isotope?

Answer 1

`100.245"amu"`

Explanation:

`M_r=(sum(M_ia))/a`, where:

• `M_r` = relative attomic mass (`g` `mol^-1`)
• `M_i` = mass of each isotope (`g` `mol^-1`)
• `a` = abundance, either given as a percent or amount of `g`

`98.225=(96.780(100-41.7)+M_i(41.7))/100`

`M_i=(98.225(100)-96.780(58.3))/41.7=100.245"amu"`