Question

7. If 1 g of oxygen element contains X atoms , what will be
the number of atoms in 1 g of aluminium ? ( Atomic
mass : 0 = 16 u , Al = 27. u)
8. Calculate the number of aluminium ions present in
0.051 g of aluminium oxide (Al,0z).
[Atomic mass : Al = 27u ; 0 = 16u]
9. The number of carbon atoms in 1g of Ca​

Answer 1

Answer:

7) No. of Particles = given mass/Gram Atomic/Molecular Mass x Avogadro's Number

Gram atomic mass of oxygen = 16u (given)

Given mass = 1g

No. of atoms = 1/16 x 6.022 x 10²²

= 0.376375 x 10²² = 3.763 x 10²¹ atoms

So, X = 3.763 x 10²¹

Similarly, for aluminum,

No of atoms = 1/27 x 6.022 x 10²²

≈ 2.230 x 10²¹ atoms

8) Given Mass = 0.051

Gram molecular mass of Aluminium Oxide =

2(27) + 3(16) = 102u

No. of aluminium ions = 2(1/0.051 x 6.022 x 10²²)

Note: we are multiplying by 2 as there are 2 aluminium ions in one aluminium oxide molecule.

No. of aluminium ions = 1.18 x 10²⁴