Question

A new compound was recently discovered and found to have an atomic weight of 342.38 amu. This element has two isotopes, the lighter of which has a mass of 340.91 amu and an abundance of 68.322%. What is the mass of the heavier isotope?

Answer 1

Answer:

The mass of heavier isotope is 345.6 amu.

Explanation:

Given data:

atomic wight of compound = 342.38 amu

lighter isotope mass = 340.91 amu

abundance of lighter isotope = 68.322%

mass of heavier isotope = ?

Solution:

average atomic mass = ( % age abundance of lighter isotope × its atomic mass) + (% age abundance of heavier isotope × its atomic mass)  / 100

percentage of heavier isotope = 100- 68.322 = 31.678

Now we will put the values in formula.

342.38  = (68.322× 340.91) + (31.678 × X) / 100

342.38 = 23291.65302 +  (31.678 × X) / 100

342.38 × 100 = 23291.65302 +  (31.678 × X)

34238 -23291.65302 =  (31.678 × X)

10946.35 / 31.678 = X

345.6 = X

The mass of heavier isotope is 345.6 amu.