Water, starch and clock reactions.

I started distilling water yesterday because chem guy needed my supply because his ran out. So i turned on the still, put my 5 gal tank on the spout and completely forgot about it.

Then, morning came.

Aside from the fact that I left my office key at home (physics guy's key opens my lab as well, lucky enough), I almost made the alarm go off due to my forgetful nature. Then I noticed a weird feeling and I asked myself, why is my sock wet? And then I saw it, about 50L of distilled water on the floor. First thing i thought was that I would get caught no matter what because i'm on a 4th floor and there's officed beneath my office. So I went downstairs to check for water damage.

Luckily, my floor is sealed with silicon, some weird polymer and layers and layers of floor wax so I think no water got through to the third floor below. Or I hope so, but there weren't any signs of water damage on the ceiling of the office below my lab.

I had to clean it up, but how?.

The problem is that my floor very uneven, thus water doesn't flow to the drain that's right in front of my sink, but to a particular spot in front of the acids locker. And the source of the the spill, the neck of the 5 gal tank, was about 10 inches from the drain. So I had to figure out a way to get rid of all the water before any electrical damage happened and most importantly, before anybody noticed.

It was 7:15am and nobody had arrived yet. I decided to sneak into the maintainance closet down the hall to get the mop bucket and the mop. I proceeded to scoop up all the water, periodically emptying the bucket into the sink and after about 20 minutes I managed to scoop all the water up. I mopped the floor dry, set my fan on high to further and quickly dry the rest and i placed the mopping equipment back into the closet down the hall. I don't think anybody knows noticed, another sneak op done right.

Hours of idle came about... nothing.

Then my boss came, chemistry guy. He asked me to prepare another demo. It's the end of the year at the school, so any experiments left undone by the students must be done via demo by the teacher. This demo is one I particularly hate because it involved starch.

You see, startch is a bitch to make properly. Yesterday I made a 2% solution for biology woman, and that took a while to mix. Today it was only 1L of 0.02% solution, pretty quick to make.

There's 2 schools of thought on how soluble starch solutions should be made. One says that the total amount of dry starch should be made into a sticky goop by adding a few drops of room temperature water and then pouring considerable volume of boiling water on the goop. I find this method to be a pain in the ass because:

1- it doesnt always work since clumps of goop have to be small in order to dissolve properly, any large goop clumps will remain goopy in solution.
2- it takes way too long and is more work because you have to boil the water first
3- the solution must cool down to room temp before you use it, adding to reason #2, and if you have 1L or more of it you're in for a loooooooooong wait.

My method is far simpler. I set the approximate volume of water needed for the solution in a beaker (today it was a 1000mL beaker), I added a magnetic stirring pill and reved up the magnetic stirrer. Once a vortex is formed due to the pill spinning, which is immediately, i add the starch little by little. And I mean LITTLE by LITTLE. If you add too much at one time, clumps will form. It might be tedious, but it's way quicker and no hot water involved. You let the stirring continue for about 15 minutes and done. You got a starch solution.


The demo in question is the hydrogen peroxide/potassium iodine clock reaction. If you know this reaction, you also know it used glacial acetic acid (mighty concentrated vinegar, a.k.a. ethanoic acid). And if you know vinegar smells, multiply that by a million and you have the smell of glacial ethanoic acid. So my lab stinks right now, but i've opened windows, started fans and extractors and it's way better now. The acid is added to the starch solution and then you add in this order the following: sodium acetate, potassium iodide and sodium thiosulfate. All at once, no need to wait for one or another. Stir to dissolve, label with a big "A", serve on a bed of romaine lettuce.

For the rest, this demo uses 1L of 3% hydrogen peroxide as solution "B", i.e. what you mix "A" with.

Both solutions are colourless. When you mix them, wait 10 seconds and boom, it turns blue. Classic.



There's a long weekend coming up. In pooradise, May 1st is the day workers are celebrated. Yes, just like commies, we celebrate May Day. Most of the world celebrates may day. I think americans started it actually, with a big riot in chicago. May 1st was the day labourer's rights were established and the world famous 8 hour crunch was established as the benchmark of employee exploitation time frame. However, americans don't celebrate may day, they celebrate labor day, in november right?

Anyway, long weekend is coming up and I have to clean up and lock tight everything in my lab. In a little bit i'll go home to get my keys and then I'll go to the bank to see why the hell a check of mine bounced if there's money in the account.

Have a happy weekend.