Our chemistry book has a diagram of a battery in the electrochemistry chapter, and I discuss that battery for a bit before explaining to my students that the basics of ACME (anode, cathode, metallic path, electrolyte) hold for every battery but that the engineering of modern lithium-ion batteries is far different from the diagram in the book.
This video - again leaning into the algorithm-rewarded longer and longer format - explains some battery basics involving the activity series, the history of the development of the lithium-ion battery, and the methods of fiery failure when the battery overheats.
This is, as Dr Derek says, a technology that has allowed our modern, battery-dependent world.
As promised last week, here's the first Veritasium video about thermite.
I'm not thrilled that Dr Derek's titles seem to be getting more clickbaity and less informative. Again this week, the video's title isn't really what the video is about. It's a minor part of the video - here addressed in about six minutes in the middle of the video - and doesn't really cover the bulk of the video's content.
With that being said, seeing thermite in slow motion and through glass is pretty stunning.
As always and as we should probably preface every conversation that we have about materials, we should lean into the reduce side of the triangle way more than we do.
But, until we get that perfected, we need to figure out better ways to recycle those materials that we use.
In this video, an Aussie company is working on e-waste recycling, particularly toward the recovery of the precious metals: palladium, gold, copper. The activity series comes in at 2:15 when the narrator says, "palladium and gold are still stuck in the solids. They're harder to dissolve."
He really means that they're harder to react and doesn't explain that it's because of their extremely low positions on the activity series that this is true.
"For the precious metals, you need something with a little more oomph."
Yeah, you would.
This company goes on to use - according to the video - microorganisms that consume and absorb heavy metals allowing the company to concentrate those and sort them from the waste. That's fascinating, and I love the idea that they went looking for microorganisms that had evolved to thrive on mine waste instead of trying to 'invent' a new process chemically. Brilliant, gents!
That doesn't seem like much, but when they go on to say that open pit gold mining nets 3-5 grams per ton of rock, that looks way more profitable.
---
And the the video gets to the environmental justice side of things. There is a cost to our consumer culture. We in the wealthy west just aren't always the ones who are paying that cost.
Man, I hope that some of these phenomenal processes that we've heard about over the decades come to fruition and that they don't all go the way of anything into oil.
I recognize those material selection diagrams at 1:35. I've posted about similar diagrams before.
This video does a great job exploring the tradeoffs among strength, weight, cost, and properties in choosing a material. In this case, it's mostly about the tradeoffs guiding when we do - and don't - use titanium.
It also covers some of the concepts of chemical and electrolytic reduction around 5:00 - and states that we don't use either of the traditional processes to purify titanium. It's amazing that anybody ever figured out some of the more complicated metals processing...um...processes. They're so remarkably complicated.
We also get an application of accidental galvanic corrosion at 8:30 where the cadmium-plated tools were leaving trace amount of cadmium on the titanium.
Titanium really sounds like a pain in the tuchus to work with.
This is famous - at least within the science teacher world - story about the hiding of a couple of Nobel prizes (gold medals) won by Jewish scientists by Neils Bohr.
I've posted the story (from NPR's quoting from The Disappearing Spoon) before, but this goes into the science of the full electron shells (particularly the d-shell) and equilibrium going on a lot more than that other article did.
Honest question - how do I make sure my data is cleared from the electronics before I let them be recycled?
The most stunning fact in this video - recovering metals like gold from e-waste is now more efficient than digging it up from the Earth.
But it makes sense if the facts (1:40) are true. If a typical gold mine has 5-6 grams of gold per ton of Earth and a ton of mobile phones (typical e-waste) contains 350 grams, that's a brilliant source of gold.
Now we just have to find ways to get to the gold.
Notice the 'nothing you do to gold does anything to it (I'm paraphrasing, admittedly)' fact? That's because it's really low on the activity series. It's a noble metal.
Oh, and the fact that we haven't ratified the Basel Convention reminds us that the US is an awful global citizen. From wikipedia, "The 10 UN member states that are not party to the treaty are East Timor, Fiji, Grenada, Haiti, San Marino, Solomon Islands, South Sudan, Tuvalu, United States, and Vanuatu."
The video is nothing but close up, sped up growth of reduced metal crystals from metallic ion solutions. There's no mention of what the anions are, but we do know that the crystals were grown via "electrocrystallization - Metal deposition actuated via electrodic reduction on the electrode surface. An electric current operates a metal deposition reaction."
We are building a 38’ wooden sailboat designed in 1934 by William Atkin. Atkin calls this particular boat “Ingrid” but our vessel will be named “Arabella”, once built we intend to take her to the most far flung corners of the world. We are documenting every aspect of the build as we go, we hope to inspire and educate people along the way and to experience as much of this wonderful world as possible in the process.
In this week's episode (or rather the episode from April 13, 2018), Steve (the guy with the awesome beard) is looking at using various metals as fasteners on the boat. Apparently it matters whether the metal is very reactive (less noble) or not very reactive (more noble).
Specifically, Steve puts various metal samples in salt water alone and in various combinations to see which metals should and should not share fasteners in the boat.
I haven't yet checked out the follow-up where Steve looks at the effects of the metal corrosion on various woods.
Alfredo Mateus is apparently pretty cool - or at least has some pretty cool ideas.
Through the Prezi above first, largely without words...
The bottle tops - hacksawed off just below the screw top collar - become flexible in hot water and can be turned into keychains. The distorted bottle tops then can show the thermoplasticity when returned to hot water.
The inflation of the preforms is a bit trickier, and the method hinted at in the Prezi is far tougher to pull off. Check out my other post about a way to successfully inflate the preforms.
Carving a can with chemistry is a variation on the aluminum can demo using a solution of either sodium hydroxide or copper (II) sulfate to react away the aluminum can. Here Mateus has used this to produce some nice lights.
The hydrophobic toys need a whole lot more explanation. The carbon compounds in soot are apparently hydrophobic and can make for a very cool 'maze' by letting the droplets roll around rather freely.
The PET molecules, though, are pretty spectacular, and they're the ones I desperately want to recreate for my classroom. I just need to figure out how to throw around a few pop rivets. And sadly, they're the only ones that are NOT covered in the related pdf of instructions.
Any chance anybody can find better instructions for the 2L bottle molecules?
Slate has put together a series called Blogging the Periodic Table written by Sam Kean (of the awesome The Disappearing Spoon). They're up to thirty-three articles so far. The last was published in June, 2011, so I'm assuming that thirty-three is where the series is going to end.
Aluminum, as the article relates, is the most common element in the Earth's crust was absolutely useless to us for centuries because it is so reactive. As the article writes...
From a world production total of perhaps a few ounces per month in the
decades before, by 1888, the largest U.S. aluminum company (the one that
became Alcoa) could produce almost 50 pounds of aluminum each day.
Within 20 years, it had to ship out 88,000 pounds per day to meet
demand. As production soared, prices plummeted. In the mid-1800s, the
first aluminum ingots on the market went for $550 per pound. Fifty years
later, not even adjusting for inflation, it cost 25 cents for the same
amount.
Check the article out. If you enjoy it, check out Kean's Disappearing Spoon, an absolute masterpiece of chemistry, material science, and story telling.
I don't think I want to go diving on those pylons, but I love that they're using the activity series right up front there to protect the steel cables in the columns. See, they make a weak battery, a weak battery, a weak battery where the zinc corrodes and prevents the steel from corroding.
That's got to be a whole lot of zinc being replaced on a pretty regular basis. I wonder how much zinc costs.
Thanks to Ryan Cox for sharing the video. As always, if you find any great videos, send 'em my way.
One of the most fascinating stories of the activity series (because there are so many, donchaknow) is that of the dissolving of two Nobel prizes (the gold medallions themselves) in a desperate rush as the Nazis marched into Copenhagen an 1940. The story involved aqua regia - a mixture of hydrochloric and nitric acids - and the heroic efforts of George de Hevesy.
The most heart-warming part of the story, then, is that de Hevesy was able to return in 1950 and recover the gold, which he then had reminted by the Nobel Prize committee for eventual presentation back to the original award winners in 1952.
The story is published by NPR who quote Sam Kean's The Disappearing Spoon.
The most potentially expensive demonstration that I've ever done was to take my gold wedding ring (not pure gold, 14K, I think) and placing it in concentrated hydrochloric acid. The activity series says that nothing should have happened, and - thankfully because I certainly hadn't cleared the demo with my wife first - nothing did. That's because I used only hydrochloric acid.
Using hydrochloric acid and nitric acid, though. Agua regia (royal water) will dissolve gold, producing - as the video above shows - chloroauric acid.
To see that gold really is non-reactive in each of the acids (and in molten NaOH, even) alone, check out the video after the jump.
I've also added a video showing how the gold can be recovered from the chloroauric acid.
I mean, really, this video has no words what so ever.
What it does have is...at 0:15 a thermite mixture placed on a heated form...at 0:23 an ignitor lit and placed in the mixture...at 0:28 a controlled hell breaking loose, peaking at about 0:35...molten iron leaking into the form at 0:45 (I think)...an awesome sound at 0:48...or maybe molten iron leaking at 0:50...I have no idea what the yellow thing does at 2:05...still glowing iron being cleaned up at 2:45...and big grinding at 3:30.
Chris, a chemistry teacher from Ottawa, CA and our shadow in Houston, spoke about aluminum purification when we talked about the labs from the National Association of Corrosion Engineers. One of the labs sees the students placing aluminum strips - from a pop can - into various solutions: cola, water, vinegar, HCl, NaOH, CuSO4. It's the more concentrated (2M) acid (HCl) andbase (NaOH) that are relevant to the video posted below.
According to Chris - and backed up by a Wikipedia article on bauxite processing - the bauxite is heated with sodium hydroxide solution. This dissolves the aluminum (since it's amphoteric, meaning it will dissolve in both acids and bases) but not the iron compounds present. The iron doesn't dissolve and creates what is industrially known as red mud. This red mud is highly basic (pH between 10 and 14 - 13 in the incident mentioned below) and all but impossible to dispose of. So the red mud - or red sludge, more prosaically - is kept in huge holding ponds...just waiting...for...um...yeah...
In 2010 a holding pond of 35.3 million cubic feet (1 billion liters, 8.4 million barrels, 264 million gallons) of the red sludge broke free from a holding pond in Hungary and covered 16 square miles, initially as a six-foot high wave of the sludge. The flooding was worst along and into the Marcal River and eventually into the Danube.
Here are three more articles related to the accident in Hungary...
Gold is pricey. I get that, but when all the steps involved in getting the gold out of the ground are lined up - as they are in this video - that priceiness makes a lot more sense.
There's another good tour through the process of extracting gold in the Nova special Hunting the Elements.
Early this week the students at ASM's corrosion-themed three-day workshop (hosted by the University of Akron's National Center for Education and Research on Corrosion and Materials Performance - that's a mouthful) got to tour the AZZ Galvanizing plan in Canton, OH. There the AZZ folks gave a great PowerPoint (which you can see here - be warned, however, that it's a 150MB pdf of the presentation, kinda big) on the advantages of and science behind the hot dip galvanizing process - about which they might be admittedly a little biased. They then took the teachers/campers to see the process in action. I - as one of those campers - can say it was a pretty impressive sight to see, particularly as the steel light post was lowered into the molten zinc which began to spit and splash due to the temperature difference of the materials.
The finished post section practically glowed from the brilliant, shiny zinc coating as it was removed from the zinc bath. Great process to see in action and great protection against corrosion.
There's so much science hanging here in this remarkably simple-to-perform demonstration.
Steve Spangler - former elementary science teacher - her explains that the kinetic energy from the ball bearing's banging together turn into thermal energy - enough to burn holes in the piece of construction paper. He then goes on to show the far cooler - to me, anyway - reaction of iron oxide (the rust on the outside of the ball bearings) and aluminum. Most folks - if they know that reaction - know it as thermite (check a few thermite reactions here).
Typically, though, the thermite reaction involves mixing aluminum and iron (III) oxide powders in a flower pot or some ceramic vessel. The reaction is then started with a separate reaction (it has high activation energy) and then produces molten iron and a huge pile of sparks. It's outstanding to watch FROM A DISTANCE. That whole FROM A DISTANCE and the need for some second reaction means that thermite is typically reserved for high school and college chemistry classes.
Spangler - who didn't come up with the idea, by the way - brings the reaction into far more manageable form by taking a rusty ball bearing (covered in iron oxide) right up against one covered in aluminum foil. Same reactants...good energy to start the reaction (from the KE of the ball bearings)...great sparks.
Yeah, it takes a little practice to get the technique down right, but it's way safer than the big thermite reaction that throws molten iron all over the place. Plus, you get to clean up the rusty ball bearing in the process.
activity series - aluminum more active than iron, so oxygen goes to aluminum
energy transfer - kinetic energy becomes thermal energy becomes chemical energy becomes light and heat energy again
corrosion - We're un-corroding the iron in favor of the aluminum.
electrochemistry - electrons are leaving the aluminum (so it's the anode) and going to the iron (so it's the cathode)
I am so happy that I just got myself a pair of these rusty ball bearings myself.
First day of awesome AP chemistry, here we come.
Update: If you're looking to buy yourself a set of these, Flinn Scientific offers a slightly larger version of these rusty steel balls (AP 6256) for (as of April, 2013, anyway) $26.60. Plus you get a couple of sheets of aluminum foil, which are easily worth like a thousand dollars or something. They also have a video on their site (that I can't figure out how to embed here)
