Question

Compute the difference in masses of 10^3 moles each of magnesium atoms and magnesium ions.

Answer 1

Mass of 1 mol i.e. 6.023x10²³ = 24 g
Mass of 10³ = 6.023x10²⁶ = 24 kg

Mg loses 2 electrons per atom hence no. of electrons lost are = 6.023x10²⁶ x 2 = 1.2 x 10²⁷

Mass of 1 electron = 9.31 x 10^-31
Therefore total mass of electrons lost = 1.2 x 10²⁷ x 9.31 x 10-31
difference in mass = 0.001121 kg
and mass of Mg ions = 24-0.001121 = 23.9989 kg