Question

Compute the difference in masses of 10³ moles each of magnesium atoms and magnesium ions.

(Mass of an electron = 9.1×10^–31 kg)

Answer 1

Mg⁺²ion = 10 electron

Mg atom = 12 electrons

Difference between Mg²⁺ and Mg = 2 moles of electrons

The difference between 103 moles of Mg and 103 moles of Mg²⁺ = 10³ × 2 moles of electrons 

Mass of 10³ × 2 moles of electrons

= 2 × 10³ × 6.022 × 10²³ × 9.1 × 10⁻³¹ kg

= 1.096 × 10⁻³ kg