Question

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.

Answer 1

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.

Sodium atom ionises an electron to form sodium ion,

$Na⟶N{a}^{+}+1e^{-1}$

For 100 moles of each sodium atom and sodium ion, there would be a difference of 100$e^{-}$ Mass of 100 moles of electrons = 5.48002 g
Mass of 1 mole of electron $=\frac{5.48002}{100}g$

∴6.022×${10}^{23}$ electrons are present in 1 mole of electron (as 1 mole =6.022×${10}^{23}$ electrons)
Mass of one electron $=\frac{5.48002}{100\times 6.022\times {10}^{23}}=0.0091\times {10}^{-28}g=9.1\times {10}^{-31}g$