Precious Bodily Fluids

According to science, fluoride is a nutrient which helps to prevent tooth decay and is added to the water supply in the interest of public health.

According to some people who aren't really good at understanding science, fluoride is a hazardous waste product (more toxic than lead!) which is added to our water by Big Dentistry to lower our children's IQs and destroy all our white blood cells. Also the Nazis used it! So there's that, too. (After visiting each of those sites, I hope to eventually study the relationship between "People Who Like Conspiracy Theories" and "People Who Don't Understand Graphic Design.")

And of course, according to General Ripper in Dr Strangelove, fluoride is a Commie plot to poison his precious bodily fluids:

Today's post was actually going to be about people who fear the chemicals in sunscreen and/or believe that suntanning has excellent health benefits, and the rest of us are just a bunch of "heliophobic" haters. I spent exactly ten minutes reading their blogs, realised that they were essentially setting their children up to suffer skin cancer, and retreated in disgust.

Instead, you get a post about water fluoridation, where the only side effect of ignorance is having your teeth fall out of your head. Let's break General Ripper's conspiracy theory down:

• "Do you realize that in addition to fluoridating water, why, there are studies underway to fluoridate salt, flour, fruit juices, soup, sugar, milk, ice cream? Ice cream, Mandrake? Children's ice cream!" Children's icecream, to the best of my knowledge, remains unfluoridated (except, of course, for any fluoridated water used in its manufacture). Deliberately added fluoride is found in municipal water supplies, and in toothpaste. It is worth noting that the protective effect of fluoride was discovered by observing the strong teeth of people who lived in areas where the water contained naturally high levels of fluoride - ten times higher than that found in fluoridated municipal water supplies. In other words, fluoridated water also occurs as an entirely natural substance.
• "...You know when fluoridation began?...1946. 1946, Mandrake. How does that coincide with your post-war Commie conspiracy, huh? It's incredibly obvious, isn't it?" Fluoridation was actually introduced in 1945, although in the Australian state of Queensland it wasn't introduced until 2008. This clearly goes some way to explaining the heightened intelligence, and indeed life essence, of Queenslanders. 
• "A foreign substance is introduced into our precious bodily fluids without the knowledge of the individual, and certainly without any choice. That's the way your hard-core Commie works." The fluoridation of water is not a secret. Scientists, dentists and governments are justifiably proud of the public health benefits of fluoridation. However, if one does not wish to partake of government-fluoridated water, then I suppose you could just dig a well in your backyard? Unless your local groundwater has fluoride in it, in which case I guess you just die of dehydration with your precious bodily fluids uncompromised. 
• "I first became aware of it, Mandrake, during the physical act of love... Yes, a profound sense of fatigue, a feeling of emptiness followed. Luckily I — I was able to interpret these feelings correctly. Loss of essence. I can assure you it has not recurred, Mandrake. Women, er, women sense my power, and they seek the life essence. I do not avoid women, Mandrake...but I do deny them my essence." Portland is the largest US city to remain unfluoridated (until 2014). It's also the US city with the highest rate of depression. Some might say it's caused by the 222 cloudy days per year, or the insufferable hipsters. Either way, it appears that even without fluoride, their life essence is faltering. 

Seriously, though: fluoride is added to water supplies for the same reason iodine is added to salt, or Vitamin D is added to milk, or folic acid is added to flour: it's a cheap, effective, equitable way to provide an important health benefit to an entire population. Fluoridation generally costs less than $1 per person per year, and each dollar spent saves $38 in further dental costs. Fluoridation is credited with a 40-70% decrease in tooth decay in children, and a 40-60% decrease in tooth loss for adults. Even with fluoridation, 51 million school days per year are lost in the US due to dental illnesses, a number which would be much higher without fluoridation. 

Fluoridation is considered one of the ten greatest public health achievements of the last century, along with vaccination and the recognition of cigarettes as a health hazard. 

I enjoy this graphic both for its pertinent information,
and for the fact that the baby looks like a unicorn.

I suspect there is very little overlap between people who have hysterics over their precious bodily fluids, and people and children who would not otherwise be able to afford dental care. Those who claim that they should be able to choose to take fluorine in tablets (as is done in communities reliant on rainwater tanks) are advocating for an alternative which is wasteful - in packaging, manufacture, and the time of doctors and pharmacists - as well as less accessible to people without the privilege of money or health education. 

If you have the money to pay for a dentist, then you have the money to buy one of the many filters available to remove fluoride from your water. So go do that, and...

No Guinea Pigs Were Harmed in the Making of this Post

I had an assignment this semester where we were asked to record a three-minute science presentation. Most people made nifty science shows for school children. I created my own sedatives and road-tested them on a pet guinea pig.

 

Homeopathy is like the Jersey Shore of pseudoscience: so outrageously, obviously awful that it seems hardly worth criticising. I have friends who feel the same way about the anti-vaccine movement, believing that it's only a fringe group of tin-hat-wearing sociopaths with a phobia of needles. But they're wrong. There are so many of these people, and they are very loud. 

Their brains were removed as part of a conspiracy
involving  Monsanto and the Illuminati.

They're loud enough to get homeopathy paid for by the NHS in the UK, and by private health insurers here in Australia. They're loud enough that they can influence large numbers of people to reconsider vaccinating their children, leading to outbreaks of deadly and preventable diseases like measles and whooping cough. They're loud enough that you can't go into a pharmacy any more without being faced with a wall of nonsense magic remedies.

Yes, homeopathic hospitals are actually a thing that exists in the UK.

In wandering the scientifically-illiterate cesspools of the internet whilst researching this video, I became so incredibly frustrated that I created this bingo card/drinking game to try to eke some humour out of the situation:

If you're going to play this as a drinking game,
I suggest using a homeopathic dilution of alcohol.

The point where someone's belief system can be summarised by "IT'S ALL A GOVERNMENT CONSPIRACY PAID FOR BIG PHARMA/BIG AGRICULTURE/BIG BUSINESS/BIG BIRD" is the point where you should stop trying to have a conversation, and hope that they get lost in the woods whilst communing with the Earth Life Force or whatever. 

I don't care about the loud people. You can't reason with them and they're not worth my time, or yours. But I do care about their kids and their pets and the random people on their Facebook friends list who see constant spam posts about chemtrails and have that tiny niggling seed of doubt planted in the back of their mind.  I hope that their kids get a good enough education to realise that Googling "ZOMG CHEMICALS IN MY EVERYTHING" doesn't count as research. I hope they don't treat their sick pets with Bach flower remedies.

I hope that one day I'll have enough posts here that whenever a reasonably intelligent acquaintance mumbles something about toxic MSG, you can just point them in this direction, and I'll provide a plain English explanation with some helpful links and a semi-relevant Chemistry Cat meme. That's really the motivation behind this whole project: trying to provide a counterpoint to all the fake science that's out there.

If you're seeing "PERMEATE FREE" or "ALUMINIUM FREE" or "GMO FREE" plastered on half the items in your supermarket, it's not at all unreasonable to expect that there might be something wrong with things that do contain permeate/aluminium/GMOs. But there's a big difference between being a person who wonders if they should find out more about these marketing ploys, versus being a person who screams "SAVE THE CHILDREN FROM ALUMINIUM, OH GOSH, WHAT AM I GOING TO MAKE MY FOIL HATS OUT OF NOW?!" I'm writing for the first group of people. (And also for people who like links to slightly ridiculous YouTube videos.)

One last thing: I graduate next year. I sure hope Scary Evil Scientists get paid as much as conspiracy theorists think we do, because I would really like a Maserati.

Formaldehyde Inside My Shampoo Forever

Warning: this post contains excessive use of memes, as well as outright mockery of contemporary "artist" Damien Hirst.

If you’ve sat in a high school biology class, you might remember that formaldehyde is the preservative in all those jars full of spiders and mouse foetuses. It’s also used in disinfectants and resins, as a preservative in pharmaceuticals, and in producing rather expensive works of contemporary art.

This is the structural formula of formaldehyde. 

Admire it now, before Damien Hirst covers it in rhinestones and decides it's been copyrighted.

Also, it's in some cosmetics! Formaldehyde, all over you! Quick, throw out all your shampoo and nail polish and go live in a cave before the chemicals come and murder your whole family.

Earlier this year, Johnson & Johnson announced that it was removing formaldehyde from its baby shampoo products - or, more specifically, it was removing a preservative which released trace amounts of formaldehyde.

Formaldehyde is an entirely natural substance - it’s found in most fruits, vegetables and dairy products. It’s also produced by your own liver as part of your everyday metabolic processes - your body has about 2.5 micrograms of formaldehyde per millilitre of blood. The body breaks ingested formaldehyde down into formic acid (the venom that’s found in ant and bee stings, incidentally). 

According to Johnson & Johnson's own toxicologist, if you sat down and drank fourteen bottles of Johnson’s Baby Shampoo, you would have ingested as much formaldehyde as you can find in one apple. However, this level of nuance seems to have been lost on the media, who responded with headlines like “Johnson & Johnson owns up to deadly formaldehyde-containing products."

The mistake that's being made here (other than my mistake of visiting a website called Natural News, which is also on a mission to stamp out water fluoridation) is a misunderstanding of the scale of the quantities involved. An excess of literally anything - formaldehyde, cyanide, sunlight, food, water, pictures of LOLcats - might do you harm. But we're exposed to trace amounts of countless chemicals every day. It's the dose that makes the poison.

So, if your body can safely handle the amount of formaldehyde in an apple, it can likely manage the tiny amount absorbed by rubbing shampoo into your hair. But instead of trying to give people a primary-school-level maths lesson, manufacturers bow to hysteria and replace innocuous ingredients with something with less name recognition - even if the replacement ingredient isn't as effective, or as rigorously tested.

There's a similar occurence in the food industry: "all-natural" stevia is used to replace aspartame as a sweetener, even though aspartame has a longer history of safe use. Why do people get hysterical about aspartame? Because it's metabolised into very small amounts of methanol - much less methanol than you would expect to find in, say, fruit juice - and then into very small amounts of Evil Formaldehyde. (As an aside, stevia - sold by the Coca-Cola company as Truvia - is purified by extraction with methanol.)

In another effort to combat The Formaldehyde Menace, almost every nail polish is suddenly wearing a label proclaiming itself "3 free!" That's free of the ingredients formaldehyde, toluene and dibutyl phthalate.

I heard you like nails, so I got you some nail-coloured nail polish

so you can colour your nails the same colour as your nails.

This sounds all well and good, except:

• Formaldehyde isn't even used in nail polishes - it's found only in nail hardening products. You might as well advertise that your nail polish is free of anthrax.
• The products used to replace the "big three" aren't necessarily any safer, only less well-known. For example, butyl acetate, found in all these 3-free polishes, is a potential carcinogen. That's not to say that coating bits of proteins on your fingertips with a minuscule amount of butyl acetate will do you harm, but by that logic, neither should toluene. 
• Unless you're actually injecting yourself with nail polish, the likelihood of you consuming a toxic amount of any of these chemicals is vanishingly small. Whilst it is possible to be allergic or sensitive to them, it is also possible to be allergic to things like peanuts. This does not mean that nobody should eat peanuts ever.

Trace amounts of formaldehyde in cosmetics aren't poison, in much the same way that dead sharks aren't art - the proponents of formaldehyde-free products are just incredibly vocal. The marketing of formaldehyde-free products is, essentially, an alarmist and cynical scam designed to separate scientifically-illiterate people from their money by selling them "alternative" products which aren't necessarily any better or safer. 

Ding Ding Ding ... Boom

Caution: This post contains Breaking Bad spoilers as well as a discussion about improvised explosives. This site is intended as an educational resource - do not attempt anything mentioned in this post at home!

A little reminder for anyone who's forgotten the Season 4 finale of Breaking Bad:

So, how did Walter White build a wheelchair bomb detonated by a bell?

Have a closer look at the benchtop during the scene where Walter is making his bomb:

Those are instant cold packs - cold packs that are activated by a chemical reaction. They contain a small bag of material inside a larger bag of water. Once you break the inner bag, it mixes with the water and cools to near-freezing. This is because the dissolution of the substance in the bag is endothermic: that is, it requires energy to happen, and it takes that energy in the form of heat from the surrounding water. The amount of energy required for the volume of fluid in the bag ends up being about 23 degrees Celcius, so if you're starting at room temperature (around 25 degrees) they cool to just above freezing temperature. (As an aside - don’t store instant cold packs in the fridge! If you do that, they’ll get so cold upon activation that they can cause frostbite.)

So, what’s the stuff inside the bag? Why, it's ammonium nitrate!

Ammonium nitrate (often abbreviated to AN, with the chemical formula NH₄NO₃) is made by combining nitric acid and ammonia. It's commonly used as a fertiliser because of its nitrogen content. But when AN is mixed with fuel to form ammonium nitrate fuel oil (ANFO) and then detonated, the AN reacts with the hydrogen and carbon in the fuel to form nitrogen, carbon dioxide, water, and a very large explosion.

AN explosives have a legitimate use in the mining industry, as shown in the video above. They also make for popular improvised explosive devices - they were the explosive used in the Oklahoma City bombing. Occasionally AN explodes completely by accident, and Wikipedia has this excellent list of all the industrial disasters caused by AN in the last century. 

If you’re wondering “why on Earth am I allowed to buy this and keep it in my first aid kit?”, it’s because it requires a very large amount of AN to make a useful explosive. (For this reason, many countries require a permit to buy AN fertiliser.) The Oklahoma City bombing involved 2,200 kg of AN, and by the time you've ripped open that many cold packs you might as well have just hijacked a fertiliser truck. 

(Note: DON'T HIJACK A FERTILISER TRUCK.)

So, Walt has taken his ice packs and mixed the AN inside with fuel. Let’s have a look underneath the wheelchair:

That looks like a pipe bomb. When ANFO - or any other explosive - detonates, it liberates a huge amount of energy. The energy builds up in the pipe until it reaches a point where the pipe’s structure can’t contain the pressure, at which point the pipe breaks and the energy is released. I'm guessing that Hector's bell was a signal for Walt to use the unreliable remote-controlled detonation he was practising earlier in his kitchen.

Pictured above: pipe, mobile phone, and the world's worst remote control

It’s possible to build a pipe bomb (or grenade, or mine, or shell) that won’t explode when it’s supposed to, but still contains either the explosives or the products of the explosion at high pressure. This is why unexploded ordnance is such a problem - there are weapons hanging around from WWII that are still dangerous.  This is one of the many reasons why you should NEVER BUILD A PIPE BOMB. Again: DON’T DO THIS. There are actually loads of explosives that can be synthesised from everyday materials (the mercury fulminate used in an earlier episode is another example) but that doesn’t change the fact that making homemade explosives is incredibly dangerous (and illegal). Don’t be this guy. Or this guy. Or this guy.

(Also, chances are that you’ll be getting your recipe from the internet, and if my Fight Club post is anything to go by, the internet is full of people who aren’t great at chemistry.)

I Can't Believe It's Not Science

I accidentally volunteered to work at an organic vegan soup kitchen earlier this year. 

It was an unsettling experience, for a number of reasons: they took donations of food for the benefit of inner-city hipsters rather than the hungry. It involved “organic” food, a term that makes people who’ve taken an actual chemistry class roll their eyes. They made mashed potatoes using margarine, which is an affront to everything I value. And, since the produce was “organic”, some of the people working in the kitchen - none of them trained cooks - believed it didn’t actually need to be washed. 

I am only a partially-trained cook - I quit culinary school after a professional chef disagreed with me over the existence of anaerobic bacteria. (True story.) However, I am trained enough to recognise grotesque breaches of food safety standards, so please trust me here: produce ought to be washed.

We all encounter food on a daily basis, and so food seems to spark a lot of the more bizarre scientific misunderstandings I come across. It makes me sad to think that people I know might be depriving themselves of an pre-exam all-nighter fuelled by Diet Coke and Mie Goreng noodles, simply because they’ve been told that aspartame and MSG will cause their internal organs to run away in the night.

So, here is a collection of food myths I’ve come across in person: in the organic vegan soup kitchen, at culinary school, posted on my Facebook wall.

“Organic produce doesn’t need to be washed! It’s chemical free!” For reasons which I have previously explained, organic produce is not chemical free. It is not intangible. It is not made of rainbows and the dreams of leprechauns. It’s made of chemicals like carbon and water and vitamins and then it’s treated with (organic!) fertilisers and herbicides and pesticides. (Unless the organic farm has decided to use manual labour instead of herbicides, in which case labourers remove weeds from the crops by hand, leading to crippling injuries.) 

When we say organic fertiliser, we generally mean compost or manure. Manure is cow poop. Cow poop was in the vicinity of your vegetables, and then your vegetables were picked by someone who probably wasn’t washing their hands on a frequent basis, and then your vegetables were transported and unloaded by more bare hands and then prodded by an untold numbers of strangers with unknown personal hygiene standards until you chose that one particular head of lettuce. WASH YOUR VEGETABLES.

“If you leave a McDonald’s cheeseburger out of its package it will never rot! It’s not even food!” A McDonald’s cheeseburger patty is made of ground beef and salt. That’s all. But a patty weighs less than fifty grams and is the size of my palm, and because of this high surface-area-to-volume ratio, it’s really easy for any moisture contained in the patty to evaporate when it’s left in the open air. Without moisture, bacteria cannot grow, and the burger will not decay. I considered test-driving this myth by using a control hamburger that wasn't dehydrated, but decided against it for two reasons:

1. If there's a cheeseburger in my house, I'm going to eat it, I don't care if it's a month old.
2. The amazing Kenji from Serious Eats already tested this myth very rigorously.

There aren't any mystery preservatives in McDonald's cheeseburgers. They turn over far too much product, far too quickly, to necessitate the expense of adding extra preservatives to their meat. Also: if the idea of salt and dehydration being used to preserve food is a new concept, then the deli counter at your local supermarket is going to Blow. Your. Mind.

“I’m, like, totally allergic to MSG.” Wow, that sucks! I can't imagine not being able to eat tomatoes or parmesan cheese or Vegemite or any other foods containing naturally-occurring glutamates. Wait - you're NOT actually allergic to glutamates? You just experience a vague sense of ill-health after overindulging in Chinese food? Well, that's been debunked. MSG also won't give you asthma. The evils of MSG, like aspartame, are one of those strange myths that's been tested for decades and debunked every time, and yet still persists through the menace of chain emails.

"But if MSG isn't dangerous, why does every single Chinese restaurant have a big NO MSG sign in their window?"

To be fair, this is a little bit backwards: in the comic, the cereal is advertised as not containing asbestos, even though none of the cereals contain asbestos. (This is similar to olive oil bottles with "NO CHOLESTEROL" written on them.) Conversely, when restaurants advertise that they don't use MSG, it's not because MSG is dangerous - it's because every other restaurant in town has the same sign. You can also see this phenomenon in the milk aisle of the supermarket, where every second bottle has suddenly become "permeate free!"

"Margarine is only one molecule away from being plastic." There are many reasons to avoid margarine, such as:

• The taste
• The taste
• The taste

However, for people who watch out for animal products and/or saturated fats, margarine is a viable butter alternative. It also lasts longer without proper refrigeration (which explains the ubiquity of Blue Band margarine in South East Asia). Is it one molecule away from being plastic? I don't know, and I don't care.

Peroxide bleach is one atom away from being water. Table salt is one atom different from hydrochloric acid. To make a food - or anything else, for that matter - there's only 118 elements to choose from, and only 98 of them occur naturally, and only 80 of those are actually stable. Pretty much everything you encounter in daily life is made of some combination of those 80 elements. Fewer than 30 of them have any dietary value. So, there's necessarily going to be a lot of overlap in the chemical composition of the food you eat.

"Jelly is made from animal hooves! Red food colouring is made from ground-up bugs! Sugar is an animal product!" Actually, these are all true - gelatin is extracted from animal bones, and the food colouring cochineal is, indeed, made from crushed insects. Refined white sugar can be filtered using bone char, which renders it an animal product if you're a strict vegan or obeying religious dietary guidelines.

"You should come eat at this organic soup kitchen!" You should probably ask to see the kitchen before you do this. Please make sure they're washing the vegetables.

On Chemical Burns, Vinegar and Liquefied Chicken Feet

“This is a chemical burn.” - Fight Club.

So says Tyler Durden, after he pours lye over the hand of Tyler Durden to teach Tyler Durden that he needs to lose control and place his life in the hands of Tyler Durden. Then, Tyler Durden pours vinegar over Tyler Durden’s hand to neutralise the burn.

(If the phrase “Tyler Durden” no longer means anything to you after reading that paragraph, you’re experiencing a phenomenon called semantic satiation.)

Does lye burn like that? Should you really pour vinegar over it? Can a chemical burn actually induce visions of Helena Bonham Carter in an ice cave?

Lye is another name for the chemical sodium hydroxide, or NaOH. You might have used it in the form of Drano, because it will quite happily dissolve whatever gunk is clogging up your sink. It is, indeed, used in soap making as an agent to saponify fat. It’s also used for disposing of larger objects such as animal carcasses and drug cartel enemies. Put simply, NaOH likes to eat things.

In its powdered form, as shown in the movie, sodium hydroxide will just sit on your skin until you get rained on, or start sweating, or find some other way to introduce moisture to it. It’s hygroscopic, which means it likes water so much it will eventually just start taking moisture from the atmosphere. When it does get wet it turns into a strong alkali, capable of turning your hand and any other body parts into a gross, soapy mess. This is why Tyler Durden kisses the back of Tyler Durden’s hand before he pours the lye over it - to leave moisture for the burn to occur. 

The burn is caused by a chemical reaction between the hydroxide (OH) part of the sodium hydroxide, and the glycerine and fatty acids (triglycerides) in the skin. The end products are soap and glycerine, which is used in the food and pharmaceutical industry (and yes, Tyler was correct when he stated "with enough soap, you can blow up anything" - glycerine is an ingredient in dynamite). 

If you spill a weak concentration of sodium hydroxide solution on your hand, you’ll experience itching and stinging, as well as the uniquely unpleasant sensation of being able to lubricate your hands with your own slowly-dissolving skin as you wash it off. Higher concentrations will cause deep burns and nerve damage, as well as blindness if you're unlucky enough to get it in your eyes, so kudos to Brad Pitt for wearing his safety goggles.

Here's a video of sodium hydroxide being used to break down a chicken foot. This is also an example of how NOT to create a sodium hydroxide solution - more on that later.

For a personal touch, below is a photo of my own foot. The little red mark is where I dropped a 20% solution of sodium hydroxide on it about six months ago. It's not particularly impressive, but it’s worth noting that at the time I spilled it on my foot, I was wearing both shoes and socks. (I'd like to pretend I did this as a public service to demonstrate the importance of safety in the lab, but actually I just broke the bottom off a test tube by smacking it against a benchtop.) Yes, it hurt; no, I did not experience delusional visions of Helena Bonham Carter.

So, imagine you’re at home one day, and your underground soap-making business is going so well that it’s time to render another pile of fat (human or otherwise). You spill sodium hydroxide on your hand, and it’s just damp enough that it starts to react with your skin. Is it time to break out some vinegar to neutralise that burn?

It’s true that the reaction between an acid and a base is a neutralisation reaction: acids have free hydrogen ions (H⁺) , and bases have hydoxides (the “OH” in NaOH - to be accurate, it's OH^- and has a negative charge). Together, they form neutral H₂O: water!

And heat. Did I mention heat? Because this reaction is exothermic, which is to say, it releases energy in the form of heat. So in addition to the chemical burn, you're also heating up your skin. In fact, the chicken-dissolving video at the beginning of this post actually demonstrated a really ill-advised method of creating a sodium hydroxide solution: adding a small amount of water to a large quantity of sodium hydroxide can cause it to boil or explode.

Warning: this next section gets ridiculously detailed, but there is a summary at the end if you'd prefer not to read 800 words about enthalpy.

If you consult the material safety data sheet (MSDS) for NaOH, you’ll see that the recommended course of action after skin contact is a visit to the safety shower - ideally, you’re going to be flushing the burn with water for at least fifteen minutes. That’s because, even though the reaction between NaOH and water is also exothermic, you’re going to have a much larger quantity of water available compared to vinegar (and the vinegar is mostly water, anyhow). Rather than just neutralising the alkali, it’s better to use a large amount of water to dilute and wash it all off.

(Before you get to dumping water on your hand, it would also be a good idea to turn that hand upside down so that any excess powder on the skin falls off. The less powder on the skin, the less powder will be reacting with water, and the less heat will be liberated.)

Let’s assume that the amount of NaOH left on Tyler Durden’s hand was around a quarter of a cup (so, just short of 70 cm³). Powdered NaOH weighs about 1 gram per cm³, so that’s about 70 g of NaOH. The molar mass - the mass of 6 x 10²³ molecules of NaOH - is around 40 g, so 70 g contains almost 2 moles of NaOH. This means that we need 2 moles of vinegar (acetic acid) to neutralise it.

Vinegar is usually 5% acetic acid by weight. Since the molar mass of acetic acid is around 60 g, that means we need 120 g, which is the amount of acid in 2.5 litres of a 5% solution. You have to aim around 2.5 litres of vinegar squarely at the burn to neutralise all of the NaOH. The amount of energy given off by this reaction is on the order of 50 kilojoules per mole, which is 100 kilojoules in total. That's enough energy to heat the entire 2.5 litres of vinegar by about 9 degrees Celcius. 

If you used a smaller volume of acid (for instance, if you reasoned that one cupful of an 8-mole-per-litre solution of acid contained the 2 moles necessary for neutralisation) the temperature change would be greater. If you were to use only one cupful of liquid, it would actually boil on contact with the sodium hydroxide. (This is why the common suggestion to wash the burn with a little bit of vinegar before rinsing with water is such a bad idea.)

These calculations assume you're taking your hand and dunking it in a tub of vinegar, rather than pouring it over the skin. In reality, much of the benefit would come from the action of using those 2.5 litres of vinegar to physically wash the sodium hydroxide from the skin. Alternatively, you could stand under a shower for fifteen minutes, which would dispense almost 150 litres of water. Dissolving 2 moles of sodium hydroxide in water also liberates almost 100 kilojoules of energy, however, in such a large volume of water the temperature change is negligible.

So, in short: you can fumble your way through opening a jug of vinegar and pouring it over your hand (which would be especially tricky if it's your dominant hand that's burned), or you can turn on a tap and dispense a much greater amount of water to rinse the skin. Either way, your best course of action is focusing on removing the sodium hydroxide powder from your hand, rather than trying to neutralise it. 

And unless you're applying water with an eye-dropper, Tyler Durden's assertion that "you can run water over your hand and make it worse" is just not true. Don't stand around with your hand burning because you're scared to put water on it! The greater the volume of water (or vinegar) you use, the more heat from the dissolution or neutralisation of the sodium hydroxide will be absorbed by the water rather than by your skin.

Obviously, nobody is actually taking chemical safety advice from Brad Pitt movies ...well, except for all these different soapmaking websites, seriously, every soapmaking website ever. One of them actually suggests pouring milk in your eye if you get some lye in there. Unless you have enough milk to irrigate your eye for fifteen minutes, this is not a good idea. I would also advise against accidentally swallowing lye and then chasing it with citrus juice, as suggested here.

Okay, so this turned out way longer than I'd planned. Here's the tl;dr version: when you dissolve NaOH in water, the energy that was holding the molecules together is released. It's called the enthalpy of dissolution. Similarly, when you neutralise NaOH with acid, it releases an amount of energy called the enthalpy of neutralisation. 

In the case of NaOH, these two enthalpies are actually pretty similar: about 50 kJ per mole of NaOH. Because the temperature change during the dissolution/neutralisation is a function of the volume of liquid used, you're better off dousing an NaOH burn in water. This is because you will have a lot more water available than you will have vinegar - to run a shower to flush the skin for fifteen minutes will use around 150 litres of water. 

Either way, the worst thing you can do is using too little water or vinegar - some soapmaking websites suggest "rubbing a splash of vinegar" on the burn. This will actually cause the NaOH to boil on your skin, creating a thermal burn on top of your chemical burn. So: don't do that.

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In the week that It Only Adds has been active, there's been just over a hundred page views, so thanks for stopping by! Over the next few posts I'll be addressing some of the most important scientific questions of our time:

• Can you really neutralise a chemical burn with vinegar, or did Tyler Durden lie to us?
• How did Walter White eliminate a drug lord using a wheelchair and instant cold packs?
• Is it possible to overdose on homeopathic sedatives?

Thanks again for visiting. Here, have a Science Hug:

Neil deGrasse Tyson and Bill Nye the Science Guy