Question

Explain the significance of Avagadro's number for a chemist.
b) Calculate the difference in the masses of one mole each of aluminium atoms and
their ions. Which one is heavier? (Given that the mass of an electron is9.1x10^-28g.atomic number of aluminium is 13.)​

Answer 1

Answer:

Mass of 1 mole of aluminium atom = the molar mass of aluminium = 27 g mole

−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 will be lost.

∴ Mass of three moles of electrons

=3×(9.1×10

−28

)×6.022×10

23

g

=27.3×6.022×10

23

g

=164.400×10

−5

g

=0.00164 g

∴ Molar mass of Al

+3

=(27−0.00164)g mol

−

=26.998g mol

−

Difference in mass=27–26.9984=0.0016 g