Q36Long answer
Compute the difference in masses of 103 moles each of magnesium atoms and magnesium ions. (Mass of an electron = 9.1×10 –31 kg)
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A Mg2+ ion and Mg atom differ by two electrons. 103 moles of Mg 2+ and Mg atoms would differ by 103 × 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