1. Calculate the moles of NaCl:
* Molarity (M) = moles of solute / liters of solution
* 0.500 M = moles of NaCl / 0.250 L (convert 250 mL to liters)
* moles of NaCl = 0.500 M * 0.250 L = 0.125 moles
2. Relate moles of NaCl to moles of Na+ ions:
* NaCl dissociates into one Na+ ion and one Cl- ion.
* Therefore, 0.125 moles of NaCl will produce 0.125 moles of Na+ ions.
3. Calculate the number of Na+ ions:
* Avogadro's number = 6.022 x 10^23 ions/mole
* Number of Na+ ions = 0.125 moles * 6.022 x 10^23 ions/mole
* Number of Na+ ions = 7.53 x 10^22 ions
Therefore, there are approximately 7.53 x 10^22 Na+ ions in 250 mL of a 0.500 M NaCl solution.
