Question

The molecular mass of aluminium chloride is 133.5 u. The atomic mass of chlorine is 35.5 u. What will be the atomic mass of aluminium ?​

Answer 1

molar mass of $AlCl_{3}$ = 133.5 u

atomic mass of $Cl$ = 35.5 u

As we know there are 3 atoms of Chlorine in Aluminium chloride, so chlorine's molar mass of 3 atoms will be :-

$Cl_{3}$ = 35.5 × 3

     = 106.5 u

Atomic mass of aluminium = 133.5 - 106.5

                                            = 27 u