1. Calculate the molar mass of NaCl:
* Na (sodium) has a molar mass of 22.99 g/mol
* Cl (chlorine) has a molar mass of 35.45 g/mol
* Molar mass of NaCl = 22.99 g/mol + 35.45 g/mol = 58.44 g/mol
2. Calculate the number of moles of NaCl:
* Moles = Mass / Molar Mass
* Moles = 0.12 g / 58.44 g/mol
* Moles ≈ 0.00205 mol
3. Convert moles to formula units:
* Avogadro's number (6.022 x 10^23) tells us the number of formula units (or molecules) in one mole of a substance.
* Formula Units = Moles x Avogadro's number
* Formula Units ≈ 0.00205 mol x 6.022 x 10^23 formula units/mol
* Formula Units ≈ 1.23 x 10^21 formula units
Therefore, 0.12 g of crystal salt contains approximately 1.23 x 10^21 NaCl formula units.
