Question

Chlorine has two isotopes. Chlorine-35 has an actual mass of 34.9689 u and chlorine-37 has a mass of

36.9659 u. In any sample of chlorine atoms, 75.771% will be chlorine-35 and 24.229% will be chlorine
37. Calculate the average atomic mass of chlorine.​

Answer 1

Answer:

34.9689×75.771+36.9659×24.229/75.771+24.229

Answer 2

Answer:

35.5 u

Explanation:

The isotopes of chlorine, found in nature are in the ratio 3 : 1.

So, in any sample of chlorine, Cl-35  will constitute 75% and Cl-37  will constitute 25%.

The proportion in which the isotopes are found in the nature is always constant.

Therefore, in any sample of chlorine, the average atomic mass will be,

 

Average atomic mass of chlorine

= (35 x 75/100) + (37 x 25/100)

= 105/4 + 37/4  

= 142/4  

= 35.5 u

The average atomic mass of chlorine is equal to 35.5 u.