Question

An element P has two isotopes with relative abundance of 65% and 35%. If the mass number of the two isotopes is X and 31 respectively, find the mass number represented by X given that the relative atomic mass of element P is 30.

Answer 1

Answer:

29.5

Explanation:

Given parameters:

Abundance of P- 30 = 65%  = 0.65

Abundance of P-31  = 35%  = 0.35

Mass number of P-30 = X

Mass number of P - 31  = 31

Relative atomic mass of substance  = 30

Unknown:

Mass number of P-30

Solution:

To solve this problem, apply the formula below;

  R.A.M  = (mass number of P-30  x Abundance of P-30) + (mass number of P-30 x abundance of P-31)

 Now insert the parameters and solve for X;

 30  = (X x  0.65) + (31 x 0.35)

 30 = 0.65X + 10.85

  30 - 10.85 = 0.65X

    19.15 = 0.65X

     X  = 29.5