Answer:
6.38×10²¹ molecules
Step-by-step explanation:
Formula for molybdenum chloride is:
Mo₂Cl₁₀
Molar mass is : (Molar mass for Mo) . 2 + (Molar mass for Cl) . 10
95.94 . 2 + 35.45 . 10 = 546.38 g/mol
We determine moles that are contained in 5.790 g of Mo₂Cl₁₀
5.790 g . 1 mol /546.38 g = 0.0106 moles
We count the molecules: 0.0106 mol . 6.02×10²³ molecules / mol =
6.38×10²¹ molecules
Remember that 6.02×10²³ is also called Avogadro's number (NA) which is the number of particles of anything, that are contained in 1 mol.