Question

A sodium atom has a mass of 22.99 u. Use Avogadro’s constant and the conversion factor
1.661 x 10–24 g/u to calculate the mass of 1.00 mol of sodium atoms.

Answer 1

Let us find the actual mass of the sodium atom:

$m_{0}(Na)=22.99u*1.661*10^{-24}g/u=3.819*10^{-23}g;$

This as a single atom, while 1 mole contains of Avogadro number of atoms:

$M_{1mol}(Na)=m_{0}(Na)*N_{A}=3.819*10^{-23}g*6.02*10^{23}=22.99g;$

Thus, the mole of sodium atoms weights 22.99 grams.