A 3.00 M solution of sodium chloride (NaCl) has 3 moles of NaCl in every liter of the solution. To find the mass/volume of the 3.00M solution, we must determine the mass of a single mole of NaCl (molar mass), then multiply that by 3. The volume is represented by the number of liters of the solution, which is 1.
The molar mass of sodium chloride is 58.44 g/mole. To find the molar mass of 3 moles, multiply 58.44 by 3. The mass of 3 moles of sodium chloride is thus 175.32 g.
Again, the volume of the compound is 1 liter. This means the mass/volume of the 3.00 M solution of NaCl = 175.32 g/liter.