Question

Ordinary chlorine gas has two isotopes \[\ce{^35_17Cl}\] and \[\ce{^37_17Cl}\] in the ratio of 3 : 1. Calculate the relative atomic mass of chlorine.

Answer 1

\[\ce{^35_17Cl : ^37_17Cl}\] = 3 : 1

∴ Total mass = (35 × 3) + (37 × 1)

= 105 + 37

= 142

∴ Relative atomic mass of chlorine = `142/4`

= 35.5