Understanding the Concepts

* Avogadro's Number: 6.022 x 10²³ is Avogadro's number, which represents the number of entities (atoms, molecules, formula units, etc.) in one mole of a substance.

* Formula Units: A formula unit is the smallest repeating unit in an ionic compound.

Calculation

1. Convert formula units to moles:

- Divide the number of formula units by Avogadro's number:

(1.26 x 10²⁴ formula units CaCl₂) / (6.022 x 10²³ formula units/mol) = 2.09 moles CaCl₂

Answer: There are 2.09 moles of CaCl₂ in 1.26 x 10²⁴ formula units.