Understanding the Concepts

* Avogadro's Number: One mole of any substance contains 6.022 x 10^23 particles (atoms, molecules, formula units, etc.). This number is known as Avogadro's number.

* Formula Units: Formula units are the smallest repeating unit in an ionic compound (like CaCl2).

Calculations

1. Convert formula units to moles:

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

1.26 x 10^24 formula units / (6.022 x 10^23 formula units/mol) = 2.09 moles CaCl2

Answer: There are 2.09 moles of CaCl2 in 1.26 x 10^24 formula units of CaCl2.