Hydrogen Desk Cannon Is Fun With Electricity and Water

Water is a stable chemical, but with the addition of a little electricity, it can be split into its component parts. The result is just the right mix of H2 and O2 to convert back into water with a bang. [Peter Sripol] has built a charming desktop cannon in just such a way.

The build consists of a contact lens canister filled with a solution of water and potassium hydroxide. By running a DC current through this solution, oxyhydrogen is produced, which then passes through a flash arrestor and into a combustion chamber. Upon the chamber is affixed a rocket, which is propelled when the charge is lit by a piezoelectric ignitor.

The chemical side of the build was easy, but it took significant experimentation to get the rocket side of things working well. Eventually success was found by creating a blast cap out of paper and hot glue which allowed the energy of the blast to be more effectively transferred to the rocket body. With this in place, the cannon is capable of firing small paper rockets in excess of 20 feet.

With the brass and copper components mounted upon stained wood, this contraption would look beautiful on any desk and would be great for assailing one’s fellow coworkers. If your office doesn’t have an explosives policy yet, once you bring this in to work, it will soon. [Peter] uses similar technology in his Nerf blasters, too. Video after the break.

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Reducing Carbon Emissions With Coal

It might seem like a paradox, but coal might hold the answer to solving carbon emission problems. The key isn’t burning it, but creating it using carbon dioxide from the atmosphere.  While this has always been possible in theory, high temperatures make it difficult in practice. However, a recent paper in Nature Communications shows how a special liquid metal electrocatalyst can convert the gas into a solid form of carbon suitable for, among other things, making high-quality capacitor electrodes. The process — you can see more about it in the video below — works at room temperatures.

It isn’t that hard to extract carbon dioxide from the air, the problem is what to do with it. Storing it as a gas or a liquid is inefficient and expensive, while converting it to a solid makes it much easier to store or even reuse for practical applications.

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Anodize Aluminum Easily

We’ve all seen brightly-colored pieces of aluminum and can identify them as anodized. But what does that mean, exactly? A recent video from [Ariel Yahni] starring [Wawa] — a four-legged assistant — shows how to create pieces like this yourself. You can see [Wawa’s] new dog tag, below.

[Ariel] found a lot of how to information on using sulphuric acid, but that’s dangerous stuff. One web page we covered years ago, though, discussed a safer chemistry. The process requires lye and a common pool chemical used to decrease pH. Sodium hydroxide isn’t super safe, but it is much less problem to buy, store, and use than battery acid.

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Ceramic Aerogel Meets Stretch Goals

Aerogels have changed how a lot of high tech equipment is insulated. Resembling frozen smoke, the gel is lightweight and has extremely low thermal conductivity. However there’s always a downside, traditional aerogel material is brittle. Any attempt to compress it beyond 20% of its original size will change the material. Researchers at UCLA and eight other universities around the world have found a new form of ceramic aerogel that can compress down to 5% of its original size and still recover. It is also lighter and able to withstand extreme temperature cycles compared to conventional material. The full paper is behind a paywall, but you can view the abstract.

Traditional aerogel is more likely to fracture when exposed to high temperatures or repeated temperature swings, but the new material is more robust. Made from boron nitride, the atoms have a hexagonal pattern which makes it stronger.

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Common Chemicals Combine To Make Metallic Sodium

There’s no debating that metallic sodium is exciting stuff, but getting your hands on some can be problematic, what with the need to ship it in a mineral oil bath to keep it from exploding. So why not make your own? No problem, just pass a few thousand amps of current through an 800° pot of molten table salt. Easy as pie.

Thankfully, there’s now a more approachable method courtesy of this clever chemical hack that makes metallic sodium in quantity without using electrolysis. [NurdRage], aka [Dr. N. Butyl Lithium], has developed a process to extract metallic sodium from sodium hydroxide. In fact, everything [NurdRage] used to make the large slugs of sodium is easily and cheaply available – NaOH from drain cleaner, magnesium from fire starters, and mineral oil to keep things calm. The reaction requires an unusual catalyst – menthol – which is easily obtained online. He also gave the reaction a jump-start with a small amount of sodium metal, which can be produced by the lower-yielding but far more spectacular thermochemical dioxane method; lithium harvested from old batteries can be substituted in a pinch. The reaction will require a great deal of care to make sure nothing goes wrong, but in the end, sizable chunks of the soft, gray metal are produced at phenomenal yields of 90% and more. The video below walks you through the whole process.

It looks as though [NurdRage]’s method can be scaled up substantially or done in repeated small batches to create even more sodium. But what do you do when you make too much sodium metal and need to dispose of it? Not a problem.

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How Do You Etch Something You Can’t Move?

We probably don’t need to tell this to the average Hackaday reader, but we’re living in a largely disposable society. Far too many things are built as cheaply as possible, either because manufacturers know you won’t keep it for long, or because they don’t want you to. Of course, the choice if yours if you wish to you accept this lifestyle or not.

Like many of us, [Erik] does not. When the painted markings on his stove become so worn that he couldn’t see them clearly, he wasn’t about to hop off to the appliance store to buy a new one. He decided to take things into his own hands and fix the poor job the original manufacturers did in the first place. Rather than paint on new markings, he put science to work and electroetched them into the metal.

Whether or not you’ve got a stove that needs some sprucing up, this technique is absolutely something worth adding to your box of tricks. Using the same methods that [Erik] did in his kitchen, you could etch an awesome control panel for your next device.

So how did he do it? Despite the scary multisyllabic name, it’s actually quite easy. Normally the piece to be etched would go into a bath of salt water for this process, but obviously that wasn’t going to work here. So [Erik] clipped the positive clamp of a 12 V battery charger to the stove itself, and in the negative clamp put a piece of gauze soaked in salt water. Touching the gauze to the stove would then eat away the metal at the point of contact. All he needed to complete the project were some stencils he made on a vinyl cutter.

We’ve previously covered using electricity to etch metal in the workshop, as well as the gorgeous results that are possible with acid etched brass. Next time you’re looking to make some permanent marks in a piece of metal, perhaps you should give etching a try.

[via /r/DIY]

Spectrometer Is Inexpensive And Capable

We know the effect of passing white light through a prism and seeing the color spectrum that comes out of the other side. It will not be noticeable to the naked eye, but that rainbow does not fully span the range of [Roy G. Biv]. There are narrowly absent colors which blur together, and those missing portions are a fingerprint of the matter the white light is passing through or bouncing off. Those with a keen eye will recognize that we are talking about spectrophotometry which is identifying those fingerprints and determining what is being observed and how much is under observation. The device which does this is called a spectrometer and [Justin Atkin] invites us along for his build. Video can also be seen below.

Along with the build, we learn how spectrophotometry works, starting with how photons are generated and why gaps appear in the color spectrum. It is all about electrons, which some of our seasoned spectrometer users already know. The build uses a wooden NanoDrop style case cut on a laser engraver. It needs some improvements which are mentioned and shown in the video so you will want to have some aluminum tape on hand. The rest of the bill of materials is covered including “Black 2.0” which claims to be the “mattest, flattest, black acrylic paint.” Maybe that will come in handy for other optical projects. It might be wise to buy first surface mirrors cut to size, but you can always make bespoke mirrors with carefully chosen tools.

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