Question

You have 3.0g of NaCl. You want to dissolve the Nal in water to make a 3.0M solution. How much water (in liters) do you need to add?

Answer 1

Find the number of moles of sodium chloride. Divide the mass by the molar mass. Then use proportions to find the volume needed.
3.00 moles : 1 L as (moles of NaCl) : x L.
Solve for x once you have figured out the number of moles of NaCl.