Question 27
The difference in the mass of 100 moles each of sodium atoms and sodium ions is 5.48002 g.Compute the mass of an electron.

A sodium atom and ion, differ by one electron. For 100 moles each of sodium atoms and ions there would be a difference of 100 moles of electrons.

Mass of 100 moles of electrons = 5.48002 g
Mass of 1 mole of electron $=\frac{5.48002}{100}g$
Mass of one electron $=\frac{5.48002}{100\times 6.022\times {10}^{23}}=0.0091\times {10}^{-23}g=9.1\times {10}^{-26}g$