HOLDING AN EXPLOSION at 20,000 fps - Smarter Every Day 156

That's brilliant.

The explosion there is wonderful and marvelous to watch. Gorgeous stuff, there.

Seriously, the explanation of the combustion and the slow-motion imagery is spectacular.

In the daytime, it's a little less thrilling.

See, because oxidizing..

Totally true unless your car is made out of iridium.

Source - XKCD

Trader Joe's Alkaline Water

So, Trader Joe's is selling alkaline water.

You know, just in case you need that stuff.

I happened to be over at the TJ's recently and took a photo of the back of the bottle to see what ingredients were that made it alkaline.

Potassium carbonate, potassium bicarbonate, and magnesium sulfate...simple enough then.

In AP chemistry we discuss the pH of salt solutions, and the first two of those salts are pretty straight forward.

K⁺¹ + H₂O --> KOH + OH^-1

Not gonna happen because that would involve the creation of a strong base solution (KOH) something that isn't feasible.

The anions, however, do react with the water to form alkaline (basic) solutions.

CO₃^-2 + H₂O <--> HCO₃^-1 + OH^-1

HCO₃^-1 + H₂O <--> H₂CO₃ + OH^-1

They would, indeed, make alkaline solutions because they're remaking weak acids.

The third salt, magnesium sulfate, is a little more complicated as both ions form weak acid/base solutions. There the K_a and K_b values have to be considered.

Mg⁺² + 2 H₂O <--> Mg(OH)₂ + 2 H⁺¹

SO₄^-2 + H₂O <--> HSO₄^-1 + OH^-1

The water, then, is definitely alkaline/basic. Is there, however, any advantage to drinking alkaline water? That's a different question entirely.

At this point, I'm certainly skeptical on the values of drinking alkaline water based on my brief bit of research. The folks who promote alkaline water seem to fit a lot of characteristics of snake oil salesmen.

I will be using the alkaline water in AP chemistry next year, however, and asking the students to explain the pH effects of the dissolved salts.

Wear your safety goggles, folks

We don't use a lot of angle grinders in high school science, but we certainly do teach a lot of - hopefully - good safety habits.

There are actual reasons why directives are made to wear your safety goggles, folks.

My source...original post...

Dave needs a dermatologist

That's a bad skin condition that Dave has there. He's all tessellated and rainbow-hued.

Of course, he's made of fifty-nine different elements, so that may not be entirely healthy for him.

You can check out the data on the website referenced at the bottom of the image, but that's way more boring than the graphic guy up above.

Will you be here tomorrow?

Wear your goggles, folks.

In fact, after watching this, I'm thinking you probably should wear your goggles all the time, not just when doing a lab experiment.

How to make rich, flavorful caramel without melting sugar

I'd always thought of caramel as being produced when sugar melted. I figured it had something to do with the Maillard reactions - though that needs proteins and sugars reacting together.

Turns out that caramelization is based on thermal decomposition which is - to quote Serious Eats...

...on the other hand, is a chemical reaction that breaks down molecular bonds to produce new substances. While it's not a perfect analogy, imagine a pile of grass clippings releasing carbon dioxide as it turns to mulch in the sun—an irreversible process with variable results (i.e., no two handfuls of mulch are exactly alike, or composted to the same degree). Instead of occurring at a specific point, thermal decomposition occurs over a range of temperatures determined by the intensity and duration of heat.

That doesn't call for any melting at all. All you have to do is heat the sucrose up high enough that it starts to decompose into other compounds.

In fact, caramel is so unlike sucrose, C12H22O11, that its nature can't be expressed by a single chemical formula. Instead, it's a mixture of caramelan (C15H18O9), caramelane (C12H9O9), caramelen (C36H48O24), caramelene (C36H25O25), caramelin (C24H26O13), and over a thousand other compounds "whose names," one scholar lamented in 1894, "science seems to have invented in a fit of despair."

In fact...

Despite a modest progression of color, the sugar goes through extreme changes in flavor every step of the way. With only one hour of toasting, it mellows with a complexity totally unlike plain sugar. After another hour, it's evocative of caramel the same way unrefined sugar hints of molasses, surely but subtly.

Within three hours, thermal decomposition liberates enough water that the sugar begins to clump as stronger caramel notes develop, changes that intensify into hour four. At five hours, the clumping effect makes granulated caramel visually identical to light brown sugar, but with a unique flavor of its own. Though undeniably caramel, it lacks the bitter notes synonymous with high-heat techniques, giving it a lighter profile. Beyond that point, thermal decomposition will finally liquefy the sugar.

Check out the full recipe and science over at Serious Eats.

Slow Mo Rainbow Flame - 4K - The Slow Mo Guys

Fire in slow motion - I'll watch that pretty much any day of the week.

In this video, the Slow Mo Guys - Gav and Dan - take tiki fuel with some additives meant to change the color of the flames and they burn it in the dark while filming it in slow motion.

Turns out that tiki fuel is made of napthas and burns much more cleanly than does kerosene - which I pretty much thought it was. Who knew?