Question

There are two main isotopes of chlorine. 75% of chlorine atoms have a mass number of 35, while 25% have a mass number of 37. Use this information to work out the relative atomic mass of chlorine.

Answer 1

Relative atomic mass = 35.5

Step-by-step explanation:

Given data:

Abundance of Cl -35 = 75%

Abundance of Cl -25 = 25%

Average atomic mass = ?

Solution:

Relative atomic mass = (abundance of 1st isotope × its atomic mass) +(abundance of 2nd isotope × its atomic mass) / 100

Relative atomic mass = (75×35)+(25×37) /100

Relative atomic mass = 2625 + 925 / 100

Relative atomic mass = 3550 / 100

Relative atomic mass = 35.5