Final answer:
To determine the number of moles in 2.07 × 10²³ formula units of CaCl₂, divide the given number of formula units by Avogadro's number.
Step-by-step explanation:
To determine the number of moles in 2.07 × 10²³ formula units of CaCl₂, we need to use Avogadro's number. Avogadro's number is defined as 6.022 × 10²³ formula units per 1 mole of a substance.
So, to find the number of moles, we divide the given number of formula units by Avogadro's number:
Number of moles = 2.07 × 10²³ formula units ÷ 6.022 × 10²³ formula units/mol
Calculating, we get:
Number of moles = 0.344 moles