Chemical Curiosities: Battery-Powered Marathon
As we hinted in our VS post’s information about the pH scale, electromagnetism has a role to play in chemistry as much as it has a role in physics. This includes various scenarios like:
- Redox reactions – The exchange of electrons between molecules or ions, thus the basis for the pH reactions we discussed already, and also the source of oxidative stress as discussed in our Hunt post on genetic mutations.
- Corrosion reactions – Another subclass of redox reactions, wherein exposure to oxygen, water, or certain other substances causes metals like iron to rust, silver to tarnish, and copper to develop that characteristic greenish-blue patina.
- Electrolysis – The passing of direct electrical current through an otherwise stable medium in order to cause a chemical reaction.
But the electrochemical subject that seems most interesting for a marathon is of course the science of batteries! What better analogy to use for a marathon cell than a cell with a 24 hour battery life?
So what exactly is a battery, and how does it offer us electricity without staying connected to a consistent electrical generator?
A battery can be any device composed of one or more electrochemical cells that are connected to two separate circuit terminals. The electrochemical cells contain substances which, when triggered by incoming electrical current (i.e. by electrolysis), will create a redox reaction with one another inside the battery casing. Usually in the cell there is one substance that will start losing its electrons and becoming positively charged through this reaction, while the other substance will start gaining those electrons and becoming negatively charged. As positive charge leaves one terminal and negative charge leaves the other terminal, this allows the battery to send electrical current into a device by using its terminals to complete an electrical circuit within that device.
Most batteries are designed to not simply transmit electricity, but to store electrical potential that is released when the battery is connected to something. This means that the chemical substances within their cells are selected to enable redox reactions to happen at just the right speed to supply adequate power for the battery’s function, but without using all the power up immediately. These batteries’ cells will keep releasing that power slowly, until no more redox reactions can take place. This has led to one way of distinguishing between battery types:
- Primary batteries – These batteries’ cells use substances that cannot be recharged after all redox reactions are finished; when they’re finished, the battery is “dead” and its components need to be recycled into a new battery before they would generate any electrical current again.
- Secondary batteries – These batteries’ cells use substances whose redox reactions can be “reversed” through recharging; they still can’t be reused forever, but they can receive hundreds if not thousands of recharges before they can no longer create sufficient redox reactions. Then they, too, need recycling.
Many, many different combinations of substances can be selected for making batteries, depending on what you want to accomplish. However, in day to day life you may be most familiar with a few extremely or increasingly common battery ingredients that either serve primary or secondary functions, such as:
- Alkaline batteries – These batteries are the disposable, primary batteries you’re probably used to buying for TV remotes, game console controllers, etc. — in letter-graded sizes like AA or AAA. Developed after older zinc-carbon cells, these batteries’ cells rely on either charging zinc and manganese, nickel and cadmium, or nickel and hydrogen. They’re called alkaline batteries because the pH of their electrolyte ingredient (usually potassium hydroxide) is higher than 7, whereas many other batteries use an acidic electrolyte.
- Lead-acid batteries – You would mostly recognize these in gas-powered cars. Although combustion engines run from burning gas, they need to ignite the gas and actually make the engine start, so a car’s battery allows for the creation of an electrical ignition spark. Over time, these batteries have also come to be used for powering other electrical components inside of vehicles. They are secondary batteries, and ingeniously they don’t even normally need to be manually recharged; your car’s alternator takes the power from the running engine and converts it to an electrical charge to keep the car’s battery as close to 100% charged as possible. But if your alternator is failing, or if the battery itself is getting old, and then especially if the car hasn’t been driven in a while, then you may need to recharge the battery from an AC-connected charging kit — or perform a classic jumpstart from another battery.
- Lithium-ion batteries – These are becoming extremely standard in modern electronic devices like laptops and phones, as well as in power tools, and if you have an electric vehicle then it runs on this instead of a lead-acid battery. Lithium-ion is becoming a popular configuration because they are also secondary batteries that can last through many recharges before they fail. However, they do have a safety downside. Their electrolytes are flammable and the cells are prone to becoming over-pressurized when damaged. Usually they present no hazard to you at all, but if you start to notice performance problems in your lithium-ion powered device, particularly if you see physical signs of battery expansion, stop using the device and investigate a replacement as soon as possible.
Because all of these batteries’ electrolytes are toxic to humans and other life, this is why it’s important to recycle them properly. Simply sending dead batteries to landfills allows their cells to eventually leak such substances into the local groundwater, becoming pollutants as they build up. If you take dead batteries to a disposal center, this is better for the environment and also helps keep the cost of battery materials down in the long run, especially in expensive cases like lithium-ion batteries because lithium mining is very challenging and even presents its own environmental risks.
Now that you know a little more about batteries, let’s power up the marathon cell and see if it finishes in 24 hours or if you power through it even sooner! Starting at 10:00 AM EST on 2/22, you will have 24 hours to complete one or more cells! Bonus & cell renaming information can be found in your in-game notifications.
Swag: The player who has earned the most points during the marathon (not the most cubes) wins the choice of a notebook or a mug, plus a sticker/magnet set! Second and third place will each also win a sticker/magnet set.