The number of formula units is calculated with the use of Avogadro's constant. That is, on the basis of Avogadro's law:
1 mole = 6.02 × 10²³ formula units
4.72 moles = x formula units
By cross multiplication, we get:
4.72 moles × 6.02 × 10²³ formula units / 1 mole = 2.841 × 10²⁴ formula units.
Thus, the number of formula units of CaCo₃ that are found in 4.72 moles calcium carbonate is 2.841 × 10²⁴.
