1. Convert mM to M:

* 50 mM = 0.050 M (1 M = 1000 mM)

2. Calculate moles of NaCl:

* Molarity (M) = moles of solute / liters of solution

* 0.050 M = moles of NaCl / 0.500 L

* moles of NaCl = 0.050 M * 0.500 L = 0.025 moles

3. Calculate grams of NaCl:

* grams of NaCl = moles of NaCl * molar mass of NaCl

* grams of NaCl = 0.025 moles * 58.44 g/mol (molar mass of NaCl)

* grams of NaCl = 1.46 g

Therefore, you would dissolve 1.46 grams of NaCl in water to make a 50 mM solution with a final volume of 500 mL.