Question

11. Calculate the number of aluminium ions present in 0.051 g
of aluminium oxide.
(Hint: The mass of an ion is the same as that of an atom of
the same element. Atomic mass of Al = 27 )​

Answer 1

Answer:

1 mole of Aluminium Oxide (Al2O3) = 2 × 27 + 3 × 16  = 102 g

So 1 mole of  ALUMINIUM OXIDE  weighs 102 g

1 mole of any substance contains 6.023x10^23 molecules

Thus 0.051g of ALUMINIUM OXIDE will contain 6.023x(10^23)x.051/102 = 6.023x(10^20)/2 "molecules "

Each molecule contains two ions of aluminium.

So total no. Of ions in the given amount of substance =  2x6.023x(10^20)/2 = 6.023x10^20