Isolation of salt from solution I just want to clarify my understanding of whether metathesis can be used to form other products by combining an acid and a base (do special rules apply whether its strong/weak acid/base)? 

Say I want to form some $\ce{Na2CrO4}$. There's many ways to do this but the most obvious one I can think of is:

$$\ce{2NaOH(aq) + H2CrO4(aq) -&gt;Na2CrO4(aq) + 2H2O}$$

Can you then just filter out the $\ce{H2O}$ to get your desired product? How would you do so? I'm used to looking at these in terms of net ionic equations where two aqueous reactants for a solid precipitate but since everything here would cancel out (except water) is this even a viable possibility?
You obviously cannot ‘filter water out’ as water is a liquid at STP and the solvent in which your reaction occurs in. However, you can evaporate your solution whereby the solvent gets removed and the lower vapour pressure contents (mainly solids or oils) will remain. While water can be more difficult to evaporate at a standard rotavap, it is by no means impossible.