Outdated Periodic Table

 

Source - XKCD

That would be so much easier to memorize.

As you can see if you look at the timeline of the Big Bang, that's about right that half an hour after the big bang, the only elements would have been hydrogen (75% of the universe's mass), helium (25%), lithium (trace amounts), and radioactive beryllium.

Of course, I'm not sure what this periodic table could've been printed on - or by whom, but that's not the point.

The rollover joke - Researchers claim to have synthesized six additional elements in the second row, temporarily named 'pentium' through 'unnilium'. - is also outstanding.

Freezing liquid nitrogen

I've done that.

Quite a few years ago, in class, I had some liquid nitrogen thanks to the parent of one of my students, and I was able - with the help of a vacuum pump - to repeat this demonstration in class.

I'm not sure my students were nearly as amazed as I was, but it's a singular occurrence for me.

Very cool...(pun intended)...

How To Make Drawings Float With A Magic Water Marker

That's pretty cool, man.

It's no Animator v Animation or anything, but it's a neat way to show that polar and nonpolar substances typically don't mix.

Burning diamonds

As they say, "Diamonds are forever."

That's what they say, anyway, but chemically it's not remotely true.

Diamonds are just a covalent network of carbon atoms and occasional impurities. Those covalent bonds are fairly easily broken in a combustion reaction at a high enough temperature.

That's why I tried to convince my wife that cubic zirconia was the fare more durable, stable, long-lasting choice to show the permanence of our love.

She wanted a diamond, though.

Green hands and green horns

A couple of years back, one of my AP chemistry students asked me if I knew why her hand turned green when she played the French horn.

It wasn't something I was familiar with, but I had a decent guess that green on the hand was a reaction with something copper-based...and brass is certainly copper based.

With a little looking up and finding the various brass compositions used in brass instrumentation - 67-89% copper in the brass used, I feel pretty certain that it's the copper corroding and creating that green residue - on the instrument and on the hand.

My student - MK of the Eastman School nowadays - said that she tried one of the suggested solutions -  lacquer on the horn - and didn't care for how it changed the tone of the instrument. If anybody has a better suggestion, I'll pass it along to MK.

Carbide cannons and lamps, oh my

Simple enough, eh?

I remember my dad saying that he used to play around with toy carbide cannons when he was growing up. By the time I was a kid, however, carbide cannons as children's toys had gone well by the wayside because of the danger involved.

The Rose Hulman Fighting Engineers (seriously), however, still fired one off in their quonset hut of a gym (since replaced) back when I was a student at Wabash College and occasionally travelling to watch the basketball team. I can't remember exactly why they were firing off the cannon. Maybe it was for their football team and I'm misremembering things. I can't find proof on the internet either way.

Check out some more carbide toys after the jump - including a far safer way to demonstrate this reaction thanks to Steve Spangler and Bob Becker.

Is NON-BUOYANT WATER Deadly?

Yes...sort of...

The video above explains that aerated water in sewage treatment plants - the ones with warning signs saying 'non-buoyant water' - might not be as deadly and non-buoyant as advertised.

From a 1985 study in Indiana, a Mythbusters episode (see below), and a Facebook/LinkedIn post, it looks like aerated water isn't quite as deadly as the signs say.

People do drown in aeration tanks from time to time, and I'm sure it's a very unpleasant way to die, but it appears that the drop in buoyancy - while very real - is apparently counteracted by the upward flow of the bubbles in those tanks. There is also a current caused by the upwelling that can create a circulation pushing any object toward the pool's walls and then downward (sort of like the bubbles in a pint of Guinness).

So, should you ignore the non-buoyant water signs? Not at all.

But is the risk not quite as risky as it's been made out to be? Probably.

Enter the crystalverse

 

In our material science class at Princeton - and in most of the matsci classes that originated from the ASM summer camps, I would imagine - we grow copper (II) sulfate crystals from solution.

It's a fairly easy lab to do, and the students have a high success rate.

For most students, that crystal growing experience is an end, but for others it's just a beginning, a taste of a much richer world of crystal growth.

For those students, crystalverse would be a great resource as it provides instructions for the diy crystal farmer whether they want to grow crystals of copper acetate, monoammonium phosphate, sucrose, alum, sodium chloride, potassium ferrioxalate, or even pyramidal crystals of sodium chloride.

In every case, the procedure is largely the same - make a solution, let the solution cool and evaporate to form seed crystals, continue to let the solution evaporate to grow the seed crystals larger. The great things about the crystalverse website is that it has loads of tips and faqs to help you troubleshoot your growing.

Making salt

Today you get a whole bunch of videos about making salt.

It seems like such a simple thing - talk salt water from the ocean and boil it down - but there's a lot more to the science of making salt including removing the calcium and magnesium impurities, allowing the crystals to grow to the desired size, and sorting those different crystal sizes.

Who knew that the rate of crystal growth would affect the size of the crystals?

More after the jump...

How cooks put their fingers in hot sauce without burning themselves

Heat =/= temperature

Temperature is the average kinetic energy of the particles in a substance.

Heat is energy transferred from one body to another due to a difference in temperature.

Hot things - like boiling water or simmering sauce - conduct energy to cool things - like your finger.

The amount of energy you get from that hot sauce depends on way more than the temperature of the sauce. More mass of sauce that you get on your finger means more molecules with that same average kinetic energy, so more total energy, so more pain.

In this video Adam switches mass out for time in contact with the sauce, but in this case that seems a fair swap.

Don't dunk your finger in hot fryer oil or hot sugar syrup. According to Adam, go ahead and dunk (or flick) your finger in hot, water- or oil-based sauces.

As always, vinegar leg on the right.

How To Accidentally Invent A Color

I've posted about Phoenician Purple before - the dye mentioned in this video as coming from snail shells. That's an amazing story, too.

The early part of this video defines pigments versus dyes. I'll admit that I didn't have any idea there was an actual distinction between those two. I am curious, though, as to whether the insoluble and soluble designation depends on the nature of the solvent. Like are some chemicals pigments in oil but dyes in water-based solutions?

Maybe I'll hunt down that in a different video.

Why dutched cocoa is different from natural cocoa

"It's Dutching time!"

Thanks, Adam.

Turns out there's some serious chemistry happening in the kitchen when you're making - and especially when you're dutching - some chocolate from scratch.

The Most Reflective Mirror In The World

Arrggghhh, Action Lab again.

I want to hunt down some of those dialectric mirrors. Their non-isotropic reflective materials sound pretty cool.

I am amazed that there is no metal in the material. It's just made of transparent polymer layers in alternating materials with different indices of refraction.

Best Rust Converter? POR-15, Eastwood, Rust-oleum Rust Reformer, Gempler's

One of my coworkers recommended this video to me, and I respect the video host's adherence to the scientific method. He tests metal from the same source, prepared in the same way, and has multiple test samples for each coating.

I'm not so sure, however, what these rust convertors actually do. I found this in the wikipedia article on rust converters...

Commercial rust converters are water-based and contain two primary active ingredients: tannic acid and an organic polymer. Tannic acid chemically converts the reddish iron oxides into bluish-black ferric tannate, a more stable material. The second active ingredient is an organic solvent such as 2-butoxyethanol (ethylene glycol monobutyl ether, trade name butyl cellosolve) that acts as a wetting agent and provides a protective primer layer in conjunction with an organic polymer emulsion. 

 

Some rust converters may contain additional acids to speed up the chemical reaction by lowering the pH of the solution. A common example is phosphoric acid, which additionally converts some iron oxide into an inert layer of ferric phosphate. Most of the rust converters contain special additives. They support the rust transformation and improve the wetting of the surface.

Looks like they're primarily tannic acid with some organic solvents.

The science seems pretty interesting, and I might show this video to my students when we discuss experimental design methods.

Reusable handwarmers that get hot by freezing

The title of this video is wrong.

There is no freezing happening. There is recrystallization happening from sodium acetate dissolved in solution.

That's not freezing - a pure liquid turning into a solid like ice turning into water. The host seems to understand that distinction, but he's sloppy on using the term freezing and freezing point somewhat misleadingly. He also is sloppy on liquid versus solution and melted versus dissolved.

Most of this video is an explanation and comparison of the two types of hand warmers - the reusable sodium acetate solution and the single-use iron rusting type. The video host explains the science behind what's happening and judges the single-use to be the better choice - something that I'll leave up to you.

I use both in class for different purposes and different chapters.

Decay Modes

Source - xkcd
Rollover text - Unlike an Iron Age collapse, a Bronze Age collapse releases energy, since copper and tin are past the iron peak on the curve of binding energy.

...so, it's funny because...

We haven't taught nuclear decay or nuclear chemistry in my first year chemistry class at Princeton in quite a few years since it was taken out of the Ohio chemistry curriculum and off of the AP exam quite a few years ago. We leave that nuclear stuff to the PHS physics department.

With all that being said, I remember the top row of decay mechanisms, and they're real. 

• Alpha decay sees the nucleus shedding two protons and two neutrons.
• Beta decay shows a neutron turning into a proton while the nucleus ejects an high-energy electron, aka a beta particle. That drawing helps us to know that Randall is drawing neutrons as shaded-in circles and protons as the 'white' or 'hollow' spheres.
• Gamma has the nucleus rearrange its particles - protons and neutrons, known collectively as baryons (though there are more baryons than just protons and neutrons.)
• Electron capture is just what it says: an electron is drawn into the nucleus, turning a proton into a neutron.
• Positron emission is also a proton turning into a neutron, but in this case it releases a position, effectively an electron with a positive charge.
• Neutron emission is pretty self-explanatory as a neutron leaves the nucleus.

Then we get to the made-up ones which lead to the jokes. For some of these, I did rely on explainxkcd to get the gist.

• Baryon panic would be insanely energetic, requiring all of the protons and neutrons to spontaneously separate, requiring a massive amount of energy to be absorbed by the nucleus.
• Omega decay is the assumed progression of alpha, beta, and gamma decay - omega being the last Greek letter in the alphabet. I guess since alpha, beta, and gamma decay give off increasingly energetic particles, omega decay would somehow give off the most energetic particle and cause death?
• Electron wilt seems to show the electrons just stopping their motion around the nucleus, wilting like a flower.
• One big nucleon shows all of the protons and neutrons 'congealing' into a single nucleon, the generic term for a particle in the nucleus. The is, I guess, kind of like a Bose-Einstein condensate but for the nucleus.
• Fungal decay gets nuclear decay and biological decay muddled up with the nucleus sprouting mushrooms.
• Collapse due to invasion by the sea peoples seems to refer to something that supposedly happened to the eastern Mediterranean during the late Bronze Age. I dunno. I had to look it up.

The rollover makes reference to the fact that the nuclear binding energy for iron-56 is the highest on the periodic table (at least among common isotopes). This is why large stars never make anything beyond iron-56 in their life cycle until they go supernova. And since bronze is made of tin and copper - both beyond iron-56 on the periodic table - a collapse of those elements releases energy according to Randall.

It's all some pretty esoteric stuff today.

Don't worry if you don't get it.