1. Calculate the molar mass of NaCl:
* Na: 22.99 g/mol
* Cl: 35.45 g/mol
* NaCl: 22.99 + 35.45 = 58.44 g/mol
2. Calculate the moles of NaCl:
* moles = mass / molar mass
* moles = 4.2 g / 58.44 g/mol = 0.0718 mol
3. Since there is one Na ion per NaCl molecule, there are 0.0718 moles of Na ions.
4. Calculate the number of Na ions:
* Number of ions = moles * Avogadro's number
* Number of ions = 0.0718 mol * 6.022 x 10^23 ions/mol
* Number of Na ions = 4.32 x 10^22 ions
Therefore, there are approximately 4.32 x 10^22 Na ions in 4.2 g of NaCl.
