What volume (in L) of 0.90% NaCl solution is needed to provide 4.7 g of NaCl? Assume the density of the solution is 1.0 g/mL.

Question

What volume (in L) of 0.90% NaCl solution is needed to provide 4.7 g of NaCl?  Assume the density of the solution is 1.0 g/mL. 

Answer 1

A 1% solution is the same contains 1g of solute per 100ml of the solution, so a 0,9% solution would contain 0.9g of the solute (NaCl, in this case) per 100mL of solution. 100mL is equivalent to 0.1L, so the 0.9% concentration can be re-written as 0.9g NaCl per 0.1L. Since we are looking for the volume of solution that gives 4.7g NaCl, we can divide by this concentration (this cancels out the g NaCl units in dimensional analysis) to get the liters of solution:

4.7 g NaCl x (0.1L NaCl solution/0.9 g NaCl) = 0.52 L NaCl solution.