Compute the difference in masses of 10 3 moles each of magnesium atoms and magnesium ions. (Mass of an electron = 9.1×10 –31 kg)

Question

Compute the difference in masses of 10 3 moles each of magnesium atoms and magnesium ions. (Mass of an electron = 9.1&#xD7;10 &#x2013;31 kg)

Philoid · Accepted Answer

A Mg atom and Mg²⁺ ion differ by two electrons.

For 10³ moles, each of magnesium atoms and ions there would be a difference of 10³ x 2 moles of electrons.

Mass of 2 ×10³ moles of electrons = 2×10³ × 6.023 ×10²³ × 9.1 ×10^–31 kg

= 2 × 6.022 × 9.1 × 10^–5kg = 109.6004 ×10^–5 kg

= 1.096 × 10^–3kg