Biology is freaky weird.
The bombardier beetle is terrifying. It's got three chemicals that are kept separate within its body until it mixes them which releases a ton of energy, heating and pressurizing the mixture into a boiling liquid that the beetle can squirt out of its...um...probably not its butt, but I'm not an entomologist
A few years back - when we were still in the previous iteration of Princeton High School - I had my AP chemistry students make cupcakes with three separate leavening methods: baking soda, baking powder & soda, and mechanical leavening (whipping egg whites). The three methods are fascinatingly different and produce very different results.
In this video Adam and his baker friend look at the differences between box cake mix and from-scratch cakes. They're not quite looking at just the leavenings, but the science behind the differences are fascinating.
I'm sometimes sad that we went with material science rather than food science as one of our science electives at Princeton. I wish I had a good curriculum for high school students to explore food science, but that would also require a cooking classroom - something that our principal at the time of the building of new Princeton High School wasn't interested in building anything that practical.
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.
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.
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.
I swear that it it total serendipity that I'm posting this on Christmas.
I schedule posts way in advance (10/1/23 is when I'm posting this one) and don't pay any attention as to when they get posted. I just line things up so they're on the next available Monday.
We couldn't get any better a time to see the redox reaction between a silver nitrate solution and a copper Chemistree, could we?
I feel like some of the above video was from some of Veritasium's previous videos because they look somewhat familiar to me.
With that being said, the video does a great job explaining what happens in fireworks.
Dr Derek starts with making rudimentary black powder (gunpowder - not the modern, smokeless version as Derek explains at 8:30) starting with the initial recipe from ancient China and moving to a more modern 75/10/15 ratio of carbon/sulfur/charcoal and then to a commercial, modern gunpowder.
From there, it's onward to testing the effects of container strength on the size of the explosion - first with a simple, cardboard tube then with a reinforced tube. He then brings in a fireworks manufacturer who explains the cardboard, spherical shells of actual fireworks and the method for launching them.
Then a bit about the methods of triggering the shells - showing black match then the craft-paper-encased quick match - including how to waterproof that trigger and how that trigger moves into the fireworks shell itself and lights the stars to produce the color and flash.
Speaking of the stars, they move into the creation of the different colors due to metallic salts and showing the individual spectra of those elements due to their electron configuration. The expert does then use some methanol to step things up a bit. (Remember kids, don't use methanol...ever.)
And the video wraps up with footage of a drone flying through the fireworks finale. I'll admit...that's pretty cool and should absolutely be watched in high res and expanded size.
TL;DR - sort of
Burning means to oxidize, which kind of means to combine with oxygen (and also kind of means to lose electrons), and metals can oxidize - we just normally call it rusting or corroding.
So, yes, metals can sort of burn but mostly it happens too slowly for us to notice it happening whereas burning happens way faster. To get that to happen, you'll need to get more metal exposed to more oxygen all at once - like by burning steel wool.
It's not pyrophoric or anything, but it's kind of neat.
No, water isn't wet.
The is water wet? question suggests a misunderstanding of a word in chemistry. A single thing cannot be wet. A liquid will cover a surface better or worse than a different liquid. The better a liquid covers a surface, the better that liquid is at 'wetting' the surface.
It's like asking what your tongue tastes like. It doesn't taste. It tastes.
So, what state of matter is fire?
I like the analogy that Hank uses at 1:05 - what state of matter is a waterfall - works nicely for me. "A waterfall is a process caused by a bunch of liquid and gas and solids in a specific situation. ... A waterfall isn't matter because it's a process."
Fire then is also a process of fuel and oxygen reacting to form other chemicals (mostly carbon dioxide and water).
Fire is not matter, and Hank says that pretty well.
Today you get four long videos about fireworks. The above is an episode of Nova from PBS on the history and chemistry of fireworks. I fully assume that I'll have to refind it eventually because Nova tends to be pretty good about deleting their episodes from YouTube when they're posted whole like this.
After the fireworks video a couple of weeks ago, I went hunting more videos to explain the chemistry of pyrotechnics, and I found a bunch of them.
We'll start this week with the shorter videos.
The one above is the most comprehensive of the short (10 min or less) videos I've found. It explains a bit of history, some of the structure of, the chemical reactions taking place in, and the colors produced in common fireworks.
Start with that one.
It isn't, however, a very pretty video. It's a lecture with an animated hand writing and drawing on a digital white board. Not the most exciting of the videos.
Probably twenty years ago I took a week long workshop "Chemistry of Pyrotechnics" at Miami University in the summer. It was a great explanation of the science that goes into creating everything from tiny backyard sparklers all the way up to giant fireworks shells.
The course was taught by people who normally taught science to fireworks makers, and they said that the workshop was their first time teaching the fireworks side to people who already knew the science. That made for a really interesting cross-educational experience.
Coincidentally, it turns out that Ed Escudero and Beth Eddy - both of whom I would later work with through ASM - took the same class.
The above video takes you through more of the mechanics of a large, professionally made pyrotechnics shell than it does the chemistry of pyrotechnics (I'm going to look for that video in a minute), but the mechanics includes a bunch of chemistry from controlling the rate of a reaction to producing the various colors.
And I just put in a request to get a copy of this textbook from the University of Akron library. Thank you, OhioLink.
That's some impressive can polishing right there.
This video from MEL Chemistry shows how to reveal the secret polymer liner that lives inside every pop can (or Coke can if you're from Southern Indiana like your friendly neighborhood blogger is) using 'drain cleaner.' I assume it's something like Drano, a very concentrated solution of primarily sodium hydroxide.
I do this experiment in class using hydrochloric acid in the 3M range, and it works just fine. Aluminum is, however, soluble in both acids and bases (not typical of most metals), so I have heard that sodium hydroxide solutions can produce the same result.
I would certainly be careful with the 'drain cleaner', folks, because it's some nasty stuff. Weirdly, I'm more comfortable using 3M HCl because it's something I use with fair regularity at school. The Drano, however, gives me a bit of an uneasy feeling. Oddly, though, Steve Spangler's video of the same demo also uses sodium hydroxide as did most of the other videos I found showing this demonstration. That might be because buying hydrochloric acid can be a bit tougher (unless you know it's also called muriatic acid and is available at most hardware stores.)
Either way, be careful if you try this at home, but it's pretty frickin' awesome to see.
What Happens When Bleach and Vinegar Are Mixed
Chlorine bleach contains sodium hypochlorite or NaOCl. Because bleach is sodium hypochlorite dissolved in water, the sodium hypochlorite in bleach actually exists as hypochlorous acid:
NaOCl + H2O ↔ HOCl + Na+ + OH-
Hypochlorous acid is a strong oxidizer. This is what makes it so good at bleaching and disinfecting. If you mix bleach with an acid, chlorine gas will be produced. For example, mixing bleach with toilet bowl cleaner, which contains hydrochloric acid, yields chlorine gas:
HOCl + HCl ↔ H2O + Cl2
Although pure chlorine gas is greenish-yellow, gas produced by mixing chemicals is diluted in air. This makes it invisible, so the only way to know it's there is by the smell and negative effects. Chlorine gas attacks mucous membranes in the eyes, throat, and lungs—these attacks can be deadly. Mixing bleach with another acid, such as the acetic acid found in vinegar, yields essentially the same result:
2HOCl + 2HAc ↔ Cl2 + 2H2O + 2Ac- (Ac : CH3COO)
There is an equilibrium between the chlorine species that is influenced by pH. When the pH is lowered, as when adding toilet bowl cleaner or vinegar, the ratio of chlorine gas is increased. When the pH is raised, the ratio of hypochlorite ion is increased. Hypochlorite ion is a less efficient oxidizer than hypochlorous acid, so some people will intentionally lower the pH of bleach to increase the oxidizing power of the chemical even though chlorine gas is produced as a result.So, I'd say that one checks out.
When these two compounds are combined, the following reaction takes place:
2 NaOCl + 2 NH3 --> 2 NaONH3 + Cl2
...
Another potential reaction, which occurs when a greater amount of bleach is added than ammonia, is this:
3 NaOCl + NH3 --> 3 NaOH + NCl3
That's sodium hydroxide and nitrogen trichloride. Nitrogen trichloride is a very toxic chemical to humans, and even if you did get close enough to ingest it, it would probably explode in your face first, as it is also a very volatile explosive.
...
Still another reaction - in three parts this time - can occur, producing hydrazine, N2H4, a component of rocket fuel) if you have more ammonia than bleach:
NH3 + NaOCl --> NaOH + NH2Cl
These two products then react with ammonia as follows:
NH3 + NH2Cl + NaOH --> N2H4 + NaCl + H2O
One last reaction occurs to stabalise the reagents:
2 NH2Cl + N2H4 --> 2 NH4Cl + N2
That last equation is of particular interest because of the amount of heat it produces. The heat is so great that it usually leads to an explosion.Again, I'm okay with staying you definitely shouldn't mix those two. I did, however, struggle to find a source with reactions that I trusted. The first two I found - this and this - didn't make sense in a few places, having missing mass in various places in their reactions.
3 NaClO + C3H6O --> CHCl3 + 2 NaOH + NaOCOCH3Acetone and isopropyl (rubbing) alcohol certainly aren't the same thing. So I'm going to leave this one as a maybe as I also found a fair number of sources that said any reaction between isopropyl alcohol and bleach would be fairly slow and likely would need a catalyst to see significant product production at room temperature.
[Peracetic acid] forms upon treatment of acetic acid with hydrogen peroxide with a strong acid catalyst.
H2O2 + CH3CO2H ⇌ CH3CO3H + H2OFrom cooksinfo.com
If you mix the two together in one bottle, a weak form of peracetic acid is formed. Peracetic Acid ( aka peroxyacetic acid) is a mixture of acetic acid and hydrogen peroxide. Peracetic Acid is primarily used for deactivation of a large variety of pathogenic micro-organisms in the industrial food industry, medical supplies and to prevent biofilm formation in paper pulp industries. It is usually produced in concentrations of 5 – 15%. This industrial formulation is toxic by inhalation, ingestion or if absorbed through skin; caustic and corrosive at concentrations > 10%; irritant at concentrations below 2%. Retail vinegar is a mixture of acetic acid and water composed of 4 to 8% acetic acid. Hydrogen peroxide at 3 % and retail versions of vinegar are an extremely diluted form of peracetic acid. Mixing the diluted form of acetic acid (known as vinegar) with 3% hydrogen peroxide forms a weak form of peracetic acid that may cause some reaction to those who are very sensitive to it – another reason, besides effectiveness, that applying the two solutions separately is recommended.So this one I'm going to say is true but a minor issue.
