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Briefly answer the following question:
Compute the difference in masses of one mole each of aluminium atoms and one mole of its ions. (Mass of an electron is 9.1×10–28 g). Which one is heavier?
Mass of 1 mole of aluminium atom = the molar mass of aluminium = 27 g mol-1.
An aluminium atom needs to lose three electrons to become an ion, \(Al_3{^+}\).
For one mole of \(Al_3{^+}\) ion, three moles of electrons are to be lost.
The mass of three moles of electrons = 3 × ( × \(10^-{^2}{^8}\)) × \(6.022\) × \(10^2{^3}\) g.
= × 6.022 × \(10^-{^5}\) g.
= × \(10^-{^5}\) g.
= 0.00164 g.
Molar mass of \(Al_3{^+}\) = (27 - 0.00164) g mol-1.
= g mol-1.
Difference = 27 - 26.9984
= g.
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