First let us calculate the number of moles:
number of moles = 0.500 g / (180 g / mol) = 2.78 x 10^-3
mol
From Avogadros number, we know that there are 6.022 x
10^23 molecules per mole, therefore:
number of molecules = 2.78 x 10^-3 mol * (6.022 x 10^23
molecules / mole)
= 1.67 x 10^21 molecules
