Question

Compute the difference in masses of one mole each of aluminum atoms and one mole of its ions. Which one is heavier? [Given : Mass of an electron is 9.1 x 10⁻²⁸g).

Explain with complete calculations & justifications.

Points : 20 ☺

Answer 1

mass of one mole of Aluminium atom ={ 13 × mass of each electron + 13 × mass of each proton + 14 × mass of each neutron} × Avogadro's constant .

we know, if atoms convert ions only transfer of electrons , in Al+3 ion , Aluminium atom loss three electrons ,

so,
mass of Al+3 ={10× mass of each electron +13 × mass of each proton + 14 × mass of each neutron} Avogadro's constant

now ,

you see mass of aluminium atom is greater then aluminium ion by , 3 electrons

difference in mass =mass of Aluminium atom -mass of aluminium ion

= 3 × mass of each electron x Avogadro's constant .

= 3 × 9.1 × 10^-28 x 6.023 x 10^23

=27.3 x 10^-28 x 6.023 x 10^23 g

=164.4 x 10^-5 g

= 1.644 x 10^-3 g

= 0.0016 g

Answer 2

mass of one mole of Aluminium atom ={ 13 × mass of each electron + 13 × mass of each proton + 14 × mass of each neutron} × Avogadro's constant .

we know, if atoms convert ions only transfer of electrons , in Al+3 ion , Aluminium atom loss three electrons ,

so,

mass of Al+3 ={10× mass of each electron +13 × mass of each proton + 14 × mass of each neutron} Avogadro's constant

now ,

you see mass of aluminium atom is greater then aluminium ion by , 3 electrons

difference in mass =mass of Aluminium atom -mass of aluminium ion

= 3 × mass of each electron x Avogadro's constant .

= 3 × 9.1 × 10^-28 x 6.023 x 10^23

=27.3 x 10^-28 x 6.023 x 10^23 g

=164.4 x 10^-5 g

= 1.644 x 10^-3 g

= 0.0016