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.