What's in Lemi Shine?

Lemi Shine is magical.  We must have the hardest water ever. Any harder and I'd be able to walk on it. Our dishes had the grossest white film on it that just kept getting thicker and grittier and grosser.  I thought we were going to have to wash dishes by hand or buy new dishes.  Then we tried adding Lemi Shine.  No joke, after 2 or 3 cycles, the dishes look like new.  I wish I had before and after pictures.  Imagine an opaque drinking glass next to a crystal clear drinking glass. Actually, the picture on the bottle could have been taken in our kitchen.

So I wanted to know what voodoo powder is in Lemi Shine that allows for such magical transformations to happen.  Looking on the innertubes, people making home-made dishwasing detergent often have a line like 'add Lemi Shine or lemon Kool-Aid packets.' So that's weird. The label on the bottle says it contains 'natural fruit acids and citric oils.' Ok, so maybe the lemon Kool-Aid isn't so weird. Here's a list of natural fruit acids.

So I turned to the MSDS in hopes that it would divulge the ingredient list.  The Lemi Shine MSDS was really easy to find, but the composition section reads:

Well, thanks.  That could not be less informative.  So my bottle contains between 61-105% of something? (maybe the rest is chemical free. oooooh!) The only actual quantitative information the MSDS provides is a pH of 3 and some LD50 data: Compound1: 3000 mg/kg (rat, oral); Compound2: 2840 mg/kg (rat, oral), 5000 mg/kg (rabbit, dermal - what did that experiment look like?)

So I guess since I'm a chemist, I should bring some into lab and figure it out myself, eh? So I did.

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Yoe the Scientist's Nano-Sized Brain

Deep in the heart of south-central Wisconsin, there lives a scientist who would prefer to remain nameless and (nearly) faceless.  We will call him Yoe.

Yoe the Scientist

Yoe is a graduate student at the University of Wisconsin, Madison. He is interested in transforming the nature of matter. Yoe is also interested in things that are very small. He combines these interests by researching nanowires made of the element silicon. Before we dive any deeper, let's talk about what the heck "nano" means. "Nano" usually refers to things that have one dimension (height, width, etc) of 1-100 nanometers. This is around 100 to 100,000 times smaller than the width of a human hair. SMALL! A nanowire is simply a wire whose diameter is around 100 nanometers or less.  A human hair could be called a "microwire," since its average diameter is around 100 micrometers.

Scanning electron micrograph of a human hair. Via The University of Wales Bioimaging Laboratory.

Yoe makes his silicon nanowires by a method that seems truly crazy to me. Not crazy in the "extremely dangerous" sense of the word (though his method is not without danger), but crazy in the "extremely awesome" sense of the word. First, he takes a chemical called silicon oxide and puts it in a long ceramic tube. He then heats the tube up to 1200 degrees Celsius (2,200 degrees Fahrenheit!) and flows a steady stream of hydrogen gas (4% in argon) through the tube. The machine he uses is called a tube furnace (clever huh?), and looks like this:

A red hote tube furnace. Image via Yoe the Scientist.

The box in the center is what creates the heat. The tube goes right through its center and is glowing red hot due to blackbody radiation. This is a cool-looking experiment!!!

Holy Crapola!!! Image via Yoe the Scientist

It's not completely clear what happens next, but here is a guess. These insanely hot conditions cause some of the solid silicon oxide molecules to jump from the bottom of the tube, into the hydrogen gas stream. During their journey down the tube the silicon oxide and hydrogen can react with one another and be transformed into the pure element silicon. Towards the edge of the furnace the temperature in the tube drops, and this causes the newly formed silicon to fall onto tiny stainless steel disks that Yoe placed there.  In his first experiment he put a bunch of disks in the tube, because the disks towards the outer edge of the tube would be cooler and the disks towards the inside of the tube would be hotter. Yoe wanted to find the "sweet spot" where the temperature was just right to allow his nanowires to form.

Nanowire experimental setup. Image adapted from one created by Yoe the Scientist

After Yoe stopped the reaction and the disks cooled down, they looked totally flat and boring aside from being slightly different colors than before. Just by looking at them, Yoe had no idea whether he had made his nanowires. So, Yoe looked at the disks with a super-powered microscope called a scanning electron microscope. These microscopes are WAY more powerful than normal visible-light microscopes, and they look like this on the inside.

Super high tech!!!!

Not all of the steel disks had nanowires on them, but one of them had millions and millions of them! They were everywhere!! Yoe was super-psyched!!! The nanowires looked like this at 1,500 times magnification (click to look at high-res version, seriously! Click!!!):

One of the steel disks that was hotter than the one shown above looked like total insanity!!! There were nano-sized wires, ribbons, spheres, and (if you look closely) corkscrews!! CLICK THIS IMAGE!!!

Yoe zoomed in on another portion of this disk and even found a nanoBRAIN! This nanobrain is 300,000 times smaller than your brain!! Check it out!!!

Yoe thinks the nanobrain started out as a nanodroplet of liquid silicon. He thinks that as the silicon cooled down, the outside surface solidified first. Then as the inside of the nanodroplet cooled and shrunk further, the solid silicon shell crinkled up--kind of like how the surface of a grape shrivels up when it is dried out to become a raisin. This is also similar to how your fingers prune up when they're in water, though the mechanism for that is a bit different.

Here's what is kind of surprising. Yoe thinks the nanobrain and the insane jumble of wires and ribbons are really cool, but he is more interested in doing experiments using the nanowires shown in the first image. You may ask, "Is Yoe some sort of dummy? Why isn't he more interested in the awesomer-looking image and the nanoBRAIN??!?" Yoe is no dummy. He is making these nanowires to study how they will work in the batteries of the future, and he prefers the nanowires in the first image for two main reasons.

#1) There are a lot of them. Their abundance, in addition to their tiny size, will make for a more powerful battery. #2) They are all pretty much the same size and shape, which makes them easier to study. If he saw something awesome happen using the insanity in the second image, it would be difficult to determine whether it was caused by the nano-sized wires, ribbons, spheres, or corkscrews. Scientists love cool-looking stuff, but they also want to know answers--and these interests don't always overlap.

The moral of the story is, Yoe the scientist had successfully made his nanowires! Here he is, celebrating his success at science!!

This post originally appeared on the blog Science Minus Details.

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High School Pressure Demonstration Injures Student: What Was the Instructor Thinking?!?

As linked over on the Chemistry Reddit, there's sad news from a suburban Chicago High School to report.  A 16 year old student at Richard High School in Oak Lawn was severely injured during a pressure demonstration when the apparatus his high school chemistry teacher was using to demonstrate increasing pressure failed.

Get this: the teacher allegedly put dry ice and some water in a plastic bottle, then tightly closed the lid.  Then, allegedly he actually passed the bottle around the class so students could physically witness the buildup of pressure.

Dumb. Dumb. Dumb.  Honestly, what was this chemistry teacher thinking?  Apparently the students may not have even been given goggles to wear.

Who knows how many years the teacher has been doing this demo serendipitously without incident.  Well, this time the bottle exploded while this student was holding the bottle.  He can no longer see out of his left eye, and he suffered hearing damage and other injuries to his hands and face.  It's unclear from the reports if he physically lost the eye or lost his sight in that eye.  The teacher is on administrative leave and the parents of the boy have filed suit.  The parents are claiming "negligence, willful and wanton misconduct and vicarious liability" and are seeking more than $150,000 in damages.

Now, I've worked with pressurized dry ice before.  For those of you who don't know, dry ice is solid carbon dioxide.  The solid carbon dioxide sublimes to gaseous carbon dioxide at room temperature and quickly becomes a gas with a volume much much larger than the original solid.  If you put all this volume in a closed container, the pressure will build and build until the container fails and explodes.  You make a bomb as soon as you put dry ice in a closed container.  The addition of water accelerates the sublimation causing the pressure to build up faster.

I've done this demonstration before at 'magic shows.'  We used a small amount of dry ice in a 2-L pop bottle.  We were outside, we had the kids and team members a good 30-40 feet away behind a fence, and we covered the pop bottle with one of those plastic mail crates to absorb the force of the exploding bottle and contain any shrapnel.

It's really loud.  Even with the mail crate atop, the explosion still throws the bottle/crate 5-10 feet in the air.  There's absolutely nothing safe about this demonstration, and there's no reason to have anyone anywhere near the bomb while the pressure is building.  ESPECIALLY don't have teenagers play hot potato with it!  Geez!

I also blogged a while ago about using liquid carbon dioxide as a green extraction technique.  To create the liquid carbon dioxide, you need to change the temperature and the pressure.  Put some dry ice in a plastic centrifuge tube, cap the tube tight enough that the pressure builds, but loose enough that the gas can still escape through the threads, and submerge the centrifuge tube in warm water.  The authors of the paper suggest the carbon dioxide inside the centrifuge tube approaches the triple point as it is converted into a liquid.  The triple point of carbon dioxide is  -56 degC, and 5.1 atm (the critical point is 31 degC and 72 atm).  5.1 atmospheres is still a big deal, and letting the gas buildup escape through the threads of the centrifuge cap is crucial to maintaining some semblance of control over the setup.  I still got admonished in the comments to that post about the safety of the extraction and the setup I constructed.

Bottom line: there is no reason to callously put dry ice in a closed container.  Just don't do it.  It really does make a bomb, and bombs really do destroy things.  It's just not worth it.  In fact, making a dry ice bomb is illegal in most jurisdictions.  As one Reddit commenter noted: "this is one of those experiments where a YouTube video will suffice."

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It's Lab Day!

Now I know I've made it.

Some of my students made me a YouTube parody video of Rebecca Black's Friday

And, yes, I do make a cameo.

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Pipettes and bulbs: always surprises for the experimentalist

A pipette bulb is a good friend to a chemist; a 5-inch or a 9-inch glass pipette is only a good backscratcher without a 'rabbit rubber', as my undergraduate stockroom would label them. (Really, I'm not kidding.) There's always a couple in my lab coat pocket.

Anyhow, I've always insisted that there is no need to force the bulb onto the pipette; pinching the pipette bulb at the very edge of the collar and gently placing the pipette snugly into the collar is all you need. In the picture to the right, you'll see an example of that having been done to the left-hand pipette. I have also maintained that you'll get significantly less suction power if you insist (as many students do) on forcing the pipette into the pipette bulb.* The pipette on the right has close to 1 cm of its end rammed into the bulb.

Yet, I am chagrined to note that there is not a significant difference in the amount of KMnO₄ solution drawn into the pipettes. How disappointing -- what will I find to disdain now?

A parting shot for a pet peeve: folks who roll the collar (if possible) down onto the pipette, as if, uh, um, er, uh, utilizing a prophylactic. That's really unnecessary. Just sayin'.

*Obviously, if you were to place the entire end of the pipette into the bulb, then you would not be able to force enough air out to generate a vacuum.

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