To calculate the mass of 5.55 × 10^22 formula units of calcium chloride (CaCl2), we can use the formula:

Mass = Number of formula units × Molar mass

The molar mass of CaCl2 is 110.98 g/mol.

Mass = (5.55 × 10^22 formula units) × (110.98 g/mol)

Mass ≈ 6.16 × 10^24 g

Therefore, the mass of 5.55 × 10^22 formula units of calcium chloride is approximately 6.16 × 10^24 grams.