Question

Ordinary chlorine has two isotopes :35Cl17 and 37Cl17 in the ratio 3:1.Calculate the relative atomic mass of chlorine?? Quick plz anybody

Answer 1

Chlorine has two isotopes namely ³⁵Cl and ³⁷Cl

³⁵Cl:³⁷Cl=3:1

Let the relative abundance of ³⁵Cl be 3x % and ³⁷Cl be x %

3x+x=100⇒4x=100⇒x=25

Relative abundance of ³⁵Cl=3×25=75%

Relative abundance of ³⁷Cl=25%

Atomic mass of chlorine=(75/100×35)+(25/100×37)

=105/4+37/4=142/4=35.5 u(Ans.)

Answer 2

Given:

Isotope one = 35Cl17

Isotope two = 37Cl17

To Find:

Relative atomic mass of chlorine

Solution:

Average atomic mass = relative abundance of  37Cl isotope × atomic mass of  37Cl isotope + relative abundance of  35Cl isotope × atomic mass of  35Cl isotope

= (37 X 0.25) + (35 X 0.75)

= 9.25 + 25.25

= 35.5 u

Answer: The relative atomic mass of chlorine is 35.5u.