Pancakes in the Lab

It's so easy to take making aqueous solutions for granted. Dump solute in water, mix. In some cases, things may be complicated by temperature, solubility issues and pH (e.g. arsenic trioxide dissolves much better in basic solutions than in neutral, silver cations and halide anions don't usually stay in solution together). In other cases, though, the problem is mechanical.

In the past few days, I was required to experiment with various additives to a particular solution. One additive is liquid, completely miscible with water, and is therefore quite easy to mix. A second additive doesn't dissolve very well and prefers to remain suspended in the solution, but it is a free flowing powder, fairly easy to disperse in a controlled way.

The third additive, however, is evil. It's like flour - an extremely fine powder that just won't disperse easily. Adding this stuff to my solution is like adding flour to milk in a pancake batter* - lumps are inevitable. However, lumps are ok in pancakes. Not ok in this particular solution. Argh. Also like flour, I can't make a slurry out of the additive first - it becomes all doughy and unmanagable. (Actually, it's worse than flour - like gelatin, the stuff swells upon the addition of water. Ick.)

In the end, my coworker had the brilliant idea of sifting the additive into the solution, with vigorous mixing. Like many theoretically brilliant ideas, it doesn't work nearly so well in practice. My arm is sore from stirring so much (stirbars don't agitate the solution well enough), and it's impossible to sift and stir simultaneously. Even worse, in the end the additive *still* clumps, although the clumps are relatively small. Next time (if there is a next time), I am making my coworker try his brilliant idea himself.

With any luck, the Powers that Be will decide to not use this third additive. With my luck, though, it will probably be the additive of choice. We shall see.

*Actually, when making pancakes the usual procedure calls for adding the liquid to the dry ingredients, but the result is still a lumpy, viscous mess.