Question

How many formula units of sodium sulfate are in 0.333 mol of Na2SO4?

Answer 1

Taking into consideration that Avogadro constant $(\mathrm{N}_{\mathrm{A}})$ is $6.02214129(27)\times 10^{23}\mathrm{mol}^{-1}$, formula units of sodium sulfate in 0.333 moles of $\mathrm{Na_2SO_4}$ are:

$$\mathrm{N} \left(\mathrm{Na_2SO_4}\right) = \mathrm{N_A} \cdot \mathrm{n} \left(\mathrm{Na_2SO_4}\right) = 6.02214129(27) \times 10^{23} \mathrm{mol}^{-1} \cdot 0.333 \mathrm{mol} = 2 \cdot 10^{23}$$

units.