The 1970’s was the decade that illuminated the threat of acid rain to the citizens of the US. It had been known to exist several years before, but the sources of the problem did their best to suppress the information. It wasn’t until the environmental damage became significant enough to draw national attention that it would lead to the US enacting regulations to stop acid rain.
Truthfully, most of the public was probably still unaware of what acid rain actually was. The default mental image that comes to the mind of the non-chemist is large drops of battery acid raining down from the heavens and devouring everything. This is not quite the case, however. Pure water has a neutral pH of 7. Normal rain is actually slightly acidic as it picks up CO2 from the air, making carbonic acid. But when this “normal” rain mixes with the byproducts of industrial plants that pump out large amounts of SO2 (sulfuric dioxide) and NO (nitrogen oxide) into the atmosphere, it becomes even more acidic – down to a pH of 3. This “acid” rain has the acidity of citrus juice, so it’s not going to set the world on fire. But it will wreak havoc on local ecosystems.
The 1990’s brought with it tough government regulations on the output of SO2 and NO by large factories, pretty much eliminating acid rain in the US. The rise and fall of acid rain is a great example of why we should educate ourselves on the basic chemistries that define our lives, even though we might not be actual chemists. In this article, we’re going back to your first year of college and hash out just what defines an acid and base. And solidify our understanding of the pH scale. It is essential for the future biohacker to have this knowledge in their toolbox.
We got quite a few tips in about a paper from Vanderbilt about a cool scrap metal battery they’ve been playing with. They made some pretty bold claims and when we fed the numbers in they pretty much say they’ve got a battery you can make at home, that can hold half as much as a lead acid, can be made out of scraps in a cave (even if you’re not Tony Stark), charge super fast,and can cycle 5,000 times without appreciable capacity loss. Needless to say that’s super cool.
Of course, science research is as broken as ever and the paper was hidden behind a paywall. Through mysterious powers such as the library and bothering people we were able to get past this cunning defense and read the paper. Unfortunately the paper reads more like a brag track than a useful experimental guide on how to build the dang battery. It’s also possible that our copy was missing some pages. Anyway, we want to do science!
Anyway, here’s what we know. The battery is based on an ancient battery called the Baghdad Battery. The ancient battery supposedly used iron and copper with a mystery electrolyte. The scrap battery, however, is made from scrap iron and scrap brass. The iron makes sense, but why brass? Well, brass has copper in it, and you can still get at it chemically even if it’s alloyed.
To that end, the next step was to throw some oxygen atoms in with those pesky Fe and Cu ones. The goal is to get a redox reaction going. If you do it right you can achieve pseudocapacitance. To to this the researchers used “common household chemicals and voltages” to anodize the iron and copper inside the brass. The press photo have them holding a gallon of muratic acid, if that helps. We don’t know, but if they can jam a few oxygen atoms in there then so can we!
After that it’s all about sitting the electrodes in a bath of potassium hydroxide. We guess you can scrape the inside of an AA for that. Anyway, the paper’s light on process but the battery seems really cool. They’re not pursuing this research for commercialization, instead going the OSHW route. They hope to get to the point where anyone can just grind up a bunch of scrap steel and brass, maybe throw it in a birdcage, anodize it, and get a super long life battery for grid use for less than a lead acid. If any of you manage to build one of these drop us a tip!
Most of us have had a science teacher desperately try to alleviate the drudgery of standardized test centric science education by dramatically putting a copper nail and a zinc nail into a potato or lemon. “Behold, we can measure a voltage with this voltmeter. If you get asked what a voltmeter is on a test, here is a definition none of you have enough experimental basis to understand,” the teacher would say as their dreams of being a true educator were crushed a little more.
It’s been said that with enough soap, one could blow up just about anything. A more modern interpretation of this thought is that with enough knowledge of chemistry, anything is possible. To that end, [Peter] has certainly been doing a good job of putting his knowledge to good use. He recently worked out a relatively inexpensive and easy way to etch metals using some chemistry skill and a little bit of electricity.
After preparing a set of stencils and cleaning the metal work surface, [Peter] sets his work piece in a salt solution. A metal bar is inserted in the other end of the bath, and both it and the work piece are connected to electrodes. The flow of electricity removes some metal from the exposed work surfaces, producing whatever patterns [Peter] wants.
One interesting thing that [Peter] found is that the voltage must stay under 6 volts. This is probably part of the reason it’s relatively easy to etch with even a wall wort. Above that, the iron work piece produces a different ion which can clog the work surface and create undesirable effects. Additionally, since his first experiments with this process he has upgraded the salt bath with magnetic stirrers. He also gets the best results in a very cold environment.
Looking at the ingredient list of some popular processed foods will produce a puzzled look on the typical hacker’s face. Tricalcium phosphate, thiamine mononitrate, zinc proteinate, pyridoxine hydrocloride… just who the hell comes up with these names anyway? It turns out that there is a method to the madness of chemical name structures. Some of them are well known, such as sodium chloride (NaCl) and hydrogen peroxide (H2O2). Others… not so much. In the early years of chemistry, chemical substances were named after their appearance, affects and uses. Baking soda, laughing gas and formic acid (formic is Latin for ant, and responsible for the sting in an ant bite) to name a few. As more and more chemical substances were discovered over time, a more structured naming convention was needed. Today, the above are known as sodium bicarbonate (NaHCO3), nitrous oxide (N2O) and a type of carboxylic acid (R – COOH, think of the “R” as a variable) respectively.
In today’s article, we’re going to talk about this naming structure, so that next time you admire the back of soup can, you won’t look so puzzled. We’ll also cover several common definitions that every novice biohacker should be familiar with as well.
[NightHawkInLight] wants what may be the impossible – a dirt cheap replacement for a laser cutter or a water jet. He’s got this crazy idea about using electrolysis to etch sheet steel parts, but he just can’t get the process to work. Sounds like a job for the Hackaday community.
In theory, electrolytic cutting of metal is pretty simple to understand. Anyone who lives in the northeast of the USA knows all about how road salt can cut holes in steel given enough time – say, one winter into payments on that new car. Adding a few electrons to the mix can accelerate the process of removing metal, but doing so in a controlled manner seems to be the crux of [NightHawkInLight]’s problem.
In his research into the method, he found a 2010 video by [InterestingProducts] of etching reed valves for DIY pulse jet engines from spring steel that makes it look easy. [NightHawkInLight] deviated from the reed valve process by substituting baking soda for salt to avoid the production of chlorine gas and changed up the masking technique by using different coatings. We applaud the empirical approach and hope he achieves his goal, but we tend to agree with frequent-Hackaday-tipline-project notable [AvE]’s assessment in the YouTube comments – the steel is just too darn thick. Once the etching starts, a third dimension is created at 90° to the surface and is then available to electrolyze, causing the corrosion to extend under the masking.
What does the Hackaday hive mind think? Is there any way to fix this process for thicker steel stock? Narrower traces, perhaps? Somehow modulating the current in the tank? Perhaps using the Hackaday logo would have helped? Chime in down below in the comments, and maybe we can all throw out our laser cutters.
Researchers recently observed negative refraction of electrons in graphene PN junctions. The creation of PN junctions in graphene is quite interesting, itself. Negative refraction isn’t a new idea. It was first proposed in 1968 and occurs when a wave bends–or refracts–the opposite way at an interface compared to what you would usually expect. In optics, for example, this can allow for refocusing divergent waves and has been the basis for some proposed invisibility cloaking devices.
In theory, negative refraction for electrons should be easy to observe at PN junctions, but in practice, the band gap voltage causes most electrons to reflect at the junction instead of refract. However, a graphene PN junction has no band gap voltage, so it should be ideal. However, previous attempts to find negative refraction in graphene were not successful.