posted by chemdummy .
You have a large amount of 7.50M stock solution. You need 1.80L of 3.00M solution for an experiment. How would you prepare the desired solution without wasting any stock solution?
The easiest way to work the problem is to use the dilution formula of
c1v1 = c2v2
7.5*v1 = 3.00*1.80L
v1 = 3.00*1.80/7.5 = 0.72L or 720 mL of stock. However, do you have a 1.80 L volumetric flask? Probably not. So I would use a 2.0L volumetric flask and
7.5*v1 = 3.00*2
and v1 = about 800 mL. You would measure 800 mL of the stock, add to the 2.0 L volumetric flask, and add water to the mark on the flask.