What does 2 vol (w/v) mean?
Weight per volume percent. It's basically the density. 

$$ w/v = \frac{mass_{solute}}{volume_{solution}} * 100 $$

Usually it includes units too, but you didn't specify. I'm guessing it means grams per liter?

For more, see http://www.ausetute.com.au/wtvol.html