Non-stick toilets, synthetic poo and saving the environment

141 billion litres of water are used to flush toilets every day.

Scientists develop slippery toilet coating that stops poo sticking,” shouted newspaper headlines last week, naturally prompting comments about the state of politics, the usual arguments about the ‘right’ way to hang toilet paper rolls, and puns of varying quality.

There was also more than one person asking WHY, given everything going on at the moment, scientists are spending their time on something which seems, well, not terribly urgent. After all, ceramic toilet bowls are already quite slippery. Toilet brushes exist. We have a myriad of toilet cleaning chemicals. Surely there are higher priorities? Attempting to deal with looming environmental disaster, say?

But here’s the thing, from an environmental point of view, flush toilets are quite significant. If you’re fortunate enough to live somewhere they’re ubiquitous it’s easy to take them for granted, but consider this: flushing even a water-efficient toilet uses at least five litres of water (much more for older models, a bit less if you use a ‘half-flush’ function). Often this is perfectly clean water which has been through water treatment, only to be immediately turned back into, effectively, sewage. Now imagine you have something a bit… ahem… sticky to flush. What do you do? You flush the toilet twice. Maybe more. You break out the toilet brush and the bottle of toilet cleaner, and then you probably flush at least one extra time to leave the bowl clean.

Using toilet cleaning chemicals often results in extra flushes.

Consider that the average person uses the toilet about five times and day and multiply up by the population and, even just in the UK, we’re looking at billions of litres of water daily. Globally, it’s estimated that 141 billion litres of fresh water are used daily for toilet flushing, and in some homes it could account for a quarter of indoor wastewater production. That’s a lot of fresh water we’re chucking, quite literally, down the toilet.

It rains a fair bit in the U.K. so, except for the occasional dry summer, Brits aren’t in the habit of worrying too much about water supply. The opposite, if anything. But we need to change our ways. In a speech in March this year, Sir James Bevan, Chief Executive of the Environment Agency, warned that the U.K. could run into serious water supply problems in 25 years due to climate change, population growth and poor water management.

Even putting those warnings to one side, treating water uses energy and resources. Filters are used which have to be cleaned and replaced, chemical coagulants and chlorine (usually in the form of low levels of chlorine dioxide) have to be added. Sometimes ozone dosing is used. The pH of the water needs to be checked and adjusted. All of these chemicals have to be produced before they’re used to treat the some 17 billion litres of water that are delivered to UK homes and businesses every day. And, of course, the whole water treatment process has to be continuously and carefully monitored, which requires equipment and people. None of this comes for free.

So, yes, saving fresh water is important. Plugging leaks and using water-saving appliances is vital. And, given that everyone has to go to the toilet several times a day, making toilets more efficient is potentially a really significant saving. An super non-stick toilet surface could mean less flushing is needed and, probably, fewer cleaning products too — saving chemical contamination.

Fresh water is a valuable resource.

The new super-slippery surface was co-developed by Jing Wang in the Department of Mechanical Engineering at the University of Michigan. It’s called a liquid-entrenched smooth surface (LESS) and is applied in two stages. First, a polymer spray, which dries to form nanoscale hair-like strands. The second spray completely covers these ‘hairs’ with a thin layer of lubricant, forming an incredibly flat, and very slippery, surface. The researchers tested the surface with various liquids and synthetic faecal matter and the difference — as seen in the video on this page — is really quite astonishing.

Hold up a moment, synthetic faecal matter? I’ll bet no one embarking on an engineering degree ever imagines that, one day, they might be carefully considering the make-up of artificial poo. But actually, when you think about it, it’s quite important. Quite aside from safety aspects and the sheer horror of the very idea, you couldn’t use the real thing to test something like this. You need to make sure it has a carefully-controlled consistency, for starters. It’s the most basic principle, isn’t it? If you want to test something, you have to control your variables.

Artificial poo is surprisingly important.

Indeed, there’s even a scale. It’s called the Bristol stool scale, and it goes from “hard” to “entirely liquid”. Synthetic poo is a mixture of yeast, psyllium, peanut oil, miso (proof, if it were needed, that miso really does improve everything), polyethylene glycol, calcium phosphate, cellulose and water. The amount of water is adjusted to match different points on the Bristol scale. Aren’t science and engineering fun?

Anyway. Back to the non-stick technology. This new surface can be applied to all sorts of materials including ceramic and metal, and it repels liquids and ‘viscoelastic solids‘ (stuff that’s stretchy but also resists flow: apart from poo, PVA slime is another example) much more effectively than other types of non-stick surfaces. In fact, the researchers say it’s up to 90% more effective than even the best repellent materials, and they estimate that the amount of water needed to clean a surface treated in this way is 10% that needed for ordinary surfaces. They were also able to show that bacteria don’t stick to LESS-coated materials, meaning that even if untreated water is used to flush a toilet, it remains hygienic without the need for extra chemicals.

The potential to cut 141 billion litres of water by a factor of ten is not to be (I’m sorry) sniffed at. Plus, in some areas, ready supplies of water and the facilities to clean toilets just aren’t available. Using LESS could, potentially, reduce the spread of infection.

By Chemystery22 - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=31161897 A graft copolymer has side chains branching off the main chain — these side chains are the “hairs” described by the researchers.

So what IS this surface treatment made of? This information wasn’t widely reported, but it seems quite important, not least because applications of LESS are estimated to last for about 500 flushes, which suggests that re-application will be needed fairly regularly and, perhaps more worryingly, whatever-it-is is passing into the wastewater supply.

Not surprisingly, there’s a certain amount of vagueness when it comes to its exact make-up, but I did find some details. Firstly, it’s what’s known as a graft polymer, that is, a polymer chain with long side chains attached — these are the “hairs” described by the researchers.

Secondly, the polymer strands are based on polydimethylsiloxane, or PDMS. This may sound terrifying, but it’s really not. PDMS (also known as dimethicone) is a silicone — a compound made up of silicon, oxygen, carbon and hydrogen. These compounds turn up all over the place. They’re used contact lenses, shampoos, and even as food additives. Oh, and condom lubricants. So… pretty harmless. In fact, they’re reported as having no harmful effects or organisms or the environment. The one downside is that PDMS isn’t biodegradable, but it is something that’s absorbed at water treatment facilities already, so nothing new would need to be put in place to deal with it.

The problem of better toilets might be more urgent than you thought.

Finally, the lubricant which is sprayed over the polymer chains in the second stage of the treatment to make the surface “nanoscopically smooth” (that is, flat on a 1 billionth of a metre scale) is plain old silicone oil, which is, again, something with a low environmental impact and generally considered to be very safe.

As always with environmental considerations it’s about choosing the least bad option, and using these coatings would certainly seem to be a far better option than wasting billions of gallons of precious fresh water.

In short, silly headlines aside, it turns out that making toilets better might be quite an important problem. Maybe it’s time to rage against the latrine.


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Let’s change the way we talk about changes

It’s nearly the end of the school year here in the U.K., traditionally a time for reflecting on what’s gone before and planning ahead for the shiny, new September coming in a mere nine weeks (sorry, teachers!). With that in mind, let’s talk about something that comes up early in most chemistry syllabuses, and which bothers me a little more each time I think about it.

Chemical reactions occur when a match burns.

It’s the concept of chemical and physical changes. For those who aren’t familiar, this is the idea that changes we observe happening to matter fall into two, broad categories: chemical changes, where new substances are made, and physical changes, where no new substances are made.

Examples of chemical changes include things like burning a match, cooking an egg, or the reaction between vinegar and baking soda. Physical changes are largely changes of state, such as melting and boiling, but also include changes such as dissolving salt in water, or grinding limestone chips to powder.

So far, so good. Except… then we start to put descriptors on these things. And that’s when the trouble starts.

multiple choice exam questionThe first problem comes with the idea that “chemical changes are irreversible.” This is often taught in early secondary science as a straight-up fact, and is so pervasive that it’s even appeared in multiple choice exam questions, like the one shown here. The student, for the record, was expected to choose option C, “the change is irreversible.”

Except. Argh. I can tell you exactly why the student has opted for D, “the change is reversible,” and it’s not because they haven’t done their revision. Quite the opposite, in fact. No, it’s because this student has learned about weak acids. And in learning about acids, this student met this symbol, ⇌, which literally indicates a reversible chemical reaction.

Yes, that’s right. Not too long after teaching students that chemical reactions are not reversible, we then explicitly teach them that they are. Indeed, this idea of chemical reversibility is such a common one, such an important concept in chemistry, that we even have a symbol for it.

Now, of course, I can explain this. When we say chemical reactions are irreversible, what we mean is “generally irreversible if they’re carried out in an open system.” In other words, when the wood in that match burns out in the open, the carbon dioxide and water vapour that form will escape to the atmosphere, never to return, and it’s impossible to recover the match to its original state.

The problem is that many chemical reactions occur in closed systems, not least a lot of reactions that happen in solution. Hence, the whole acids thing, where we talk about weak acids “partially dissociating” into ions.

Then there’s that entire topic on the Haber process…

Can I be the only one to think that this is rather a lot of nuance to expect teenagers to keep in their head? It’s nothing short of confusing. Should we really be saying one thing in one part of a course, and the literal opposite in another? To be clear, this isn’t even a GCSE vs. A level thing – these ideas appear in the same syllabus.

Melting is a change of state, in this case from (solid) ice to (liquid) water.

All right, okay, let’s move along to the idea that physical changes are reversible. That’s much more straightforward, isn’t it? If I melt some ice, I can re-freeze it again? If I boil some water, I can condense it back into the same volume of liquid… well… I can if I collect all vapour. If I do it in a closed system. The opposite of the condition we imposed on the chemical reactions. Er. Anyway…

We might just about get away with this, if it weren’t for the grinding bit. If physical changes are truly readily reversible, then we ought to be able to take that powder we made from the limestone lumps and make it back into a nice single piece again, right? Right?

See, this is the problem. What this is really all about is entropy, but that’s a fairly tricky concept and one that’s not coming up until A level chemistry.

Okay. Instead of talking about reversible and irreversible, let’s talk about bond-breaking and bond-forming. That’s fine, isn’t it? In chemical changes, bonds are broken and formed (yep) and in physical changes, they aren’t.

Except….

Let’s go back to water for a moment. Water has the formula H2O. It’s made up of molecules where one oxygen atom is chemically bonded to two hydrogen atoms. When we boil water, we don’t break any of those bonds. We don’t form hydrogen and oxygen gas when we boil water; making a hot cup of tea would be a lot more exciting if we did. So we can safely say that boiling water doesn’t involve breaking any bonds, right? We-ell…

Water molecules contain covalent bonds, but the molecules are also joined by (much weaker) hydrogen bonds.

The trouble is that water contains something called hydrogen bonds. We usually do a bit of a fudge here and describe these as “intermolecular forces,” that is, forces of attraction between molecules. This isn’t inaccurate. But the clue is in the name: hydrogen bonds are quite, well, bond-y.

When water boils, hydrogen bonds are disrupted. Although the bonds in individual H2O molecules aren’t broken, the hydrogen bonds are. Which means… bonds are broken. Sort of.

But we’re probably on safe ground if we talk about the formation of new substances. Aren’t we?

Except….

What about dissolving? If I dissolve hydrogen chloride gas, HCl, in water, that’s a physical change, right? I haven’t made anything new? Or… have I? I had molecules with a covalent bond between the hydrogen and the chlorine, and now I have… er… hydrochloric acid (note, that’s a completely different link to the one I used back there), made up of H+ and Cl- ions mingled with water molecules.

So… it’s…. a chemical change? But wait. We could (I don’t recommend it) evaporate all that water away, and we’d have gaseous HCl again. It’s reversible.

Solid iodine is silvery-grey, but iodine vapour is a brilliant violet colour.

Hm. What about the signs that a chemical change is occurring? Surely we’re all right there? Fizzing: that’s a sign of a chemical change. Except… are you sure you know the difference between boiling and fizzing? It’s basically all bubbles, after all. Vapour? But, steam is a vapour, isn’t it? Although, on the other hand, water is a product of several chemical reactions. Colour changes? Check out what happens when you heat a small amount of solid, silvery-grey iodine so that it sublimes (spoiler: there’s a colour change).

Is anyone else really confused by now?

You should be. Your students almost certainly are.

There are, in short, more exceptions to every single one of these rules that there are for that “i before e” thing you learned in English (a rule, incidently, which is particularly galling for scientists who constantly have to deal with weights and heights).

Where do we go from here? I think it’s probably time we asked ourselves why we’re even teaching this concept in the first place. Really, it’s there to get students to think about the difference between changes of state and chemical reactions.

I suspect we need to worry about this rather less than we are: most children are very good at identifying changes of state. They do it instinctively. They only start getting confused about it when we teach them a lot of rules which they then try to apply. I’m pretty sure that’s not the way teaching is supposed to work.

A complicated arrangement of chemical glassware

This could definitely be simpler.

If I had my way, I’d ditch the physical and chemical change labels altogether and, instead, just talk about changes of state and chemical reactions. There is precisely one differentiator between these two, and it is: have we made any new stuff? If the answer is no, it’s a change of state. If the answer is yes, then a chemical reaction has occurred. Job done. (And yes, this would squarely define gaseous hydrogen chloride dissolving in water to form hydrochloric acid as a chemical reaction, and I have no problem at all with that.)

I say we change the way we talk about changes: chemistry has a reputation for being tricky, and this sort of confusing, contradictory thing is part of the reason why.


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Let’s speed up the rate at which we recognise our female chemists

A little while back now I was researching my post on water when I came across a scientist which I hadn’t heard of before. And that was odd, because this person was one of the first to propose the idea of catalysis, which is a pretty important concept in chemistry, in fact, in science in general. Surely the name should be at least a bit familiar. Shouldn’t it?

And yet it wasn’t, and the more I read, the more surprised I was. Not only was this person clearly a brilliant thinker, they were also remarkably prescient.

Elizabeth Fulhame’s book was first published in 1794 (image by the Science History Institute, Public Domain)

So who was it? Her name was Elizabeth Fulhame, and we know very little about her, all things considered. Look her up and you won’t find any portraits, or even her exact dates of birth and death, despite the fact that her book, An Essay on
Combustion,
was published in more than one country and she, a Scottish woman, was made an honorary member of the Philadelphia Chemical Society in 1810 — remarkable achievements for the time.

As well as describing catalytic reactions for the first time, that book — first published in 1794 and surprisingly still available today — also contains a preface which includes the following:

But censure is perhaps inevitable; for some are so ignorant,
that they grow sullen and silent, and are chilled with horror
at the sight of any thing, that bears the semblance of learning,
in whatever shape it may appear; and should the spectre
appear in the shape of a woman, the pangs, which they suffer,
are truly dismal.

Obviously women are interested in physics. And also, apparently, in staring wistfully into open vacuum chambers whilst wearing unnecessary PPE (stock photos are great, aren’t they?)

Fulhame clearly did not suffer fools gladly (I think I would’ve liked her), and had also run across a number of people who felt that women were not capable of studying the sciences.

Tragically, 225 years later, this attitude still has not entirely gone away. Witness, for example, the recent article featuring an interview with Alessandro Strumia, in which he claimed that women simply don’t like physics. There were naturally a number of excellent rebuttals to this ludicrous claim, not least a brilliant annotated version of the article by Shannon Palus — which I recommend because, firstly, not behind a paywall and secondly, very funny.

Unfortunately, despite the acclaim she received at the time, Fulhame was later largely forgotten. One scientist who often gets the credit for “discovering” catalysis is Berzelius. There is no doubt that he was a remarkable chemist (you have him to thank for chemical notation, for starters), but he was a mere 15 years old when Fulhame published her book.

The RSC’s Breaking the Barriers report was published in 2018

In November last year, the Royal Society of Chemistry (RSC) launched its ‘Breaking the Barriers’ report, outlining issues surrounding women’s retention and progression in academia. As part of this project, they commissioned an interview with Professor Marina Resmini, Head of the Chemistry Department at Queen Mary University of London.

She pointed out that today there is an almost an equal gender split in students studying chemistry at undergraduate level in the United Kingdom, but admitted that there is still much to be done, saying:

“The two recent RSC reports ‘Diversity Landscape of the Chemical Sciences’ and ‘Breaking the Barriers’ have highlighted some of the key issues. Although nearly 50% of undergraduate students studying to become chemists are female, the numbers reaching positions of seniority are considerably less.”

Professor Resmini was keen to stress that there are many supportive men in academia, and that’s something we mustn’t forget. Indeed, this was true even in Fulhame’s time. Thomas P. Smith, a member of the Philadelphia Chemical Society’s organizing committee, applauded her work, saying “Mrs. Fulham has now laid such bold claims to chemistry that we can no longer deny the sex the privilege of participating in this science also.” Which may sound patronising to 21st century ears, but it was 1810 after all. Women wouldn’t even be trusted to vote for another century, let alone do tricky science.

I think I’ve found Strumia’s limousine; it’s bright red, very loud, and can only manage short distances.

Speaking of patronising comments, another thing that Strumia said in his interview was, “It is not as if they send limousines to pick up boys wanting to study physics and build walls to keep out the women.”

This is one of those statements that manages, at the same time, to be both true and also utterly absurd. Pupils, undergraduates, post-grads and post-docs do not exist in some sort of magical vacuum until, one day, they are presented with a Grand Choice to continue, or not, with their scientific career. Their decision to stop, if it comes, is influenced by a thousand, often tiny, things. Constant, subtle, nudges which oh-so-gently push them towards, or away, and which start in the earliest years of childhood. You only need to spend five minutes watching the adverts on children’s television to see that girls and boys are expected to have very different interests.

Textbooks may be studied by girls, but they rarely mention the work of female scientists.

So let’s end with another of Professor Resmini’s comments: that the work of past female scientists deserves greater recognition than it has received. This could not be more true, and this lack of representation is exactly one of those nudges I mentioned. Pick up a chemistry textbook and look for the pictures of female scientists: there might be a photo of Marie Curie, if you’re lucky. Kathleen Lonsdale usually gets a mention in the section on benzene in post-GCSE texts. But all too often, that’s about it. On the other hand, pictures of Haber, J. J. Thompson, Rutherford, Avogadro and Mendeleev are common enough that most chemistry students could pick them out of a lineup.

We should ask ourselves about the message this quietly suggests: that women simply haven’t done any “serious” chemistry (this is not the case, of course) and… perhaps never will?

Online, things have begun to shift. Dr Jess Wade has famously spent many, many hours adding the scientific contributions of women to Wikipedia, for example. It’s time things changed in print, too. Perhaps we could begin by starting the rates of reaction chapter in chemistry texts with a mention of Fulhame’s groundbreaking work.


EDIT: After I posted this, I learned that the Breaking Chemical Bias project is currently taking suggestions on the missing women scientists in the chemistry curriculum. I filled in the form for Fulhame, naturally! If this post has made you think of any other good examples, do head on over and submit their names.


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The Chronicles of the Chronicle Flask: 2018

As has become traditional, I’m finishing off this year with a round-up of 2018’s posts. It’s been a good year: a few health scares which turned out to be nothing much to worry about, one which turned out to be a genuine danger, a couple of cool experiments and some spectacular shiny balls. So without further ado, here we go…

Things were a bit hectic at the start of this year (fiction writing was happening) and as a result January was quiet on the blog. But not on the Facebook page, where I posted a couple of general reminders about the silliness of alkaline diets which absolutely exploded, achieving some 4,000 shares and a reach (so Facebook tells me anyway) of over half a million people. Wow. And then I posted a funny thing about laundry symbols which went almost as wild. It’s a strange world.

February featured BPA: an additive in many plastics.

In February I wrote a piece about BPA (Bisphenol A), which was the chemical scare of the day. There’s always one around January/February time. It’s our penance for daring to enjoy Christmas. Anyway, BPA is a chemical in many plastics, and of course plastic waste had become – and remains – a hot topic. BPA is also used in a number of other things, not least the heat sensitive paper used to produce some shopping receipts. It’s not a harmless substance by any means, but it won’t surprise anyone to learn that the risks had, as is usually the case, been massively overstated. In a report, the European Food Safety Authority said that the health concern for BPA is low at their estimated levels of exposure. In other words, unless you’re actually working with it – in which case you should have received safety training – there’s no need to be concerned.

In March I recorded an episode for the A Dash of Science podcast, and I went on to write a post about VARD, which stands for Verify, Author, Reasonableness and Date. It’s my quick and easy way of fact-checking online information – an increasingly important skill these days. Check out the post for more info.

April ended up being all about dairy and vitamin D.

April was all about dairy after a flare-up on Twitter on the topic, and went on to talk about vitamin D. The bottom line is that everyone in the UK should be taking a small vitamin D supplement between about October and March, because northern Europeans simply can’t make vitamin Din their skin during these months (well, unless they travel nearer to the equator), and it’s not a nutrient we can easily get from our food. Are you taking yours?

May featured fish tanks, following a widely reported story about a fish-owner who cleaned out his tank and managed to release a deadly toxin that poisoned his entire family. Whoops. It turns that this was, and is, a real risk – so if you keep fish and you’ve never heard of this before, do have a read!

In June I wrote about strawberries, and did a neat experiment to show that strawberries could be used to make pH indicator. Who knew? You do, now! Check it out if you’re looking for some chemistry to amuse yourself over the holidays (I mean, who isn’t?). Did you know you can make indicators from the leaves of Christmas poinsettia plants, too?

Slime turned up again in July. And December. And will probably keep on rearing its slimy head.

July brought a subject which has turned up again recently: slime. I wrote about slime in 2017, too. It’s the gift that keeps on giving. This time it flared up because the consumer magazine and organisation Which? kept promoting research that, they claimed, showed that slime toys contain dangerous levels of borax. It’s all rather questionable, since it’s not really clear which safety guidelines they’re applying and whether they’re appropriate for slime toys. Plus, the limits that I was able to find are migration limits. In other words, it’s not appropriate to measure the total borax content of the slime and declare it dangerous – they should be looking at the amount of borax which is absorbed during normal use. Unless your child is eating slime (don’t let them do that), they’re never going to absorb enough borax to do them any harm. In other words, it’s a storm in a slimepot.

August was all about carbon dioxide, after a heatwave spread across Europe and there was, bizarrely, a carbon dioxide shortage which had an impact on all sorts of things from fizzy drinks to online shopping deliveries. It ended up being a long-ish post which spanned everything from the formation of the Earth, the discovery of carbon dioxide, fertilisers and environmental concerns.

September featured shiny, silver balls.

In September I turned my attention to a chemical reaction which is still to this day used to coat the inside of glass decorations with a thin layer of reflective silver, and has connections with biochemistry, physics and astronomy. Check it out for some pretty pictures of silver balls, and my silver nitrate-stained fingers.

In October I was lucky enough to go on a ‘fungi forage’ and so, naturally, I ended up writing all about mushrooms. Did you know that a certain type of mushroom can be used to make writing ink? Or that some mushrooms change colour when they’re damaged? No? You should go back and read that post, then! (And going back to April for a moment, certain mushrooms are one of the few sources of vitamin D.)

Finally, November ended up being all about water, marking the 235th anniversary of the day that Antoine Lavoisier formally declared water to be a compound. It went into the history of water, how it was proven to have the formula H2O, and I even did an experiment to split water into hydrogen and oxygen in my kitchen – did you know that was possible? It is!

As December neared, the research for my water piece led me to suggest to Andy Brunning of Compound Interest that this year’s Chemistry Advent might feature scientists from the last 24 decades of chemistry, starting in the 1780s (with Lavoisier and Paulze) and moving forward to the current day. This turned out to be a fantastic project, featuring lots of familiar and not quite so-familiar scientists. Do have a look if you didn’t follow along during December.

And that’s it for this year. I hope it’s been a good one for all my readers, and I wish you peace and prosperity in 2019! Suggestions for the traditional January Health Scare, anyone? (Let’s hope it’s not slime again, I’m getting really tired of that one now…)


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What is Water? The Element that Became a Compound

November 2018 marks the 235th anniversary of the day when Antoine Lavoisier proved water to be a compound, rather than an element.

I’m a few days late at the time of writing, but November 12th 2018 was the 235th anniversary of an important discovery. It was the day, in 1783, that Antoine Lavoisier formally declared water to be a compound, not an element.

235 years seems like an awfully long time, probably so long ago that no one knew anything very much. Practically still eye of newt, tongue of bat and leeches for everyone, right? Well, not quite. In fact, there was some nifty science and engineering going on at the time. It was the year that Jean-François Pilâtre de Rozier and François Laurent made the first untethered hot air balloon flight, for example. And chemistry was moving on swiftly: lots of elements had been isolated, including oxygen (1771, by Carl Wilhelm Scheele) and hydrogen (officially by Henry Cavendish in 1766, although others had observed it before he did).

Cavendish had reported that hydrogen produced water when it reacted with oxygen (known then as inflammable air and dephlogisticated air, respectively), and others had carried out similar experiments. However, at the time most chemists favoured phlogiston theory (hence the names) and tried to interpret and explain their results accordingly. Phlogiston theory was the idea that anything which burned contained a fire-like element called phlogiston, which was then “lost” when the substance burned and became “dephlogisticated”.

Cavendish, in particular, explained the fact that inflammable air (hydrogen) left droplets of “dew” behind when it burned in “common air” (the stuff in the room) in terms of phlogiston, by suggesting that water was present in each of the two airs before ignition.

Antoine-Laurent Lavoisier proved that water was a compound. (Line engraving by Louis Jean Desire Delaistre, after a design by Julien Leopold Boilly.)

Lavoisier was very much against phlogiston theory. He carried out experiments in closed vessels with enormous precision, going to great lengths to prove that many substances actually became heavier when they burned and not, as phlogiston theory would have it, lighter. In fact, it’s Lavoisier we have to thank for the names “hydrogen” and “oxygen”. Hydrogen is Greek for “water-former”, whilst oxygen means “acid former”.

When, in June 1783, Lavoisier found out about Cavendish’s experiment he immediately reacted oxygen with hydrogen to produce “water in a very pure state” and prove that the mass of the water which formed was equal to the combined masses of the hydrogen and oxygen he started with.

He then went on to decompose water into oxygen and hydrogen by heating a mixture of water and iron filings. The oxygen that formed combined with the iron to form iron oxide, and he collected the hydrogen gas over mercury. Thanks to his careful measurements, Lavoisier was able to demonstrate that the increased mass of the iron filings plus the mass of the collected gas was, again, equal to the mass of the water he had started with.

Water is a compound of hydrogen and oxygen, with the formula H2O.

There were still arguments, of course (there always are), but phlogiston theory was essentially doomed. Water was a compound, made of two elements, and the process of combustion was nothing more mysterious than elements combining in different ways.

As an aside, Scottish chemist Elizabeth Fulhame deserves a mention at this point. Just a few years after Lavoisier she went on to demonstrate through experiment that many oxidation reactions occur only in the presence of water, but the water is regenerated at the end of the reaction. She is credited today as the chemist who invented the concept of catalysis. (Which is a pretty important concept in chemistry, and yet her name never seems to come up…)

Anyway, proving water’s composition becomes a lot simpler when you have a ready supply of electricity. The first scientist to formally demonstrate this was William Nicholson, in 1800. He discovered that when leads from a battery are placed in water, the water breaks up to form hydrogen and oxygen bubbles, which can be collected separately at the submerged ends of the wires. This is the process we now know as electrolysis.

You can easily carry out the electrolysis of water at home.

In fact, this is a really easy (and safe, I promise!) experiment to do yourself, at home. I did it myself, using an empty TicTac box, two drawing pins, a 9V battery and a bit of baking soda (sodium hydrogencarbonate) dissolved in water – you need this because water on its own is a poor conductor.

The drawing pins are pushed through the bottom of the plastic box, the box is filled with the solution, and then it’s balanced on the terminals of the battery. I’ve used some small test tubes here to collect the gases, but you’ll be able to see the bubbles without them.

Bubbles start to appear immediately. I left mine for about an hour and a half, at which point the test tube on the negative terminal (the cathode) was completely full of gas, which produced a very satisfying squeaky pop when I placed it over a flame.

The positive electrode (the anode) ended up completely covered in what I’m pretty sure is a precipitate of iron hydroxide (the drawing pins presumably being plated steel), which meant that very little oxygen was produced after the first couple of minutes. This is why in proper electrolysis experiments inert graphite or, even better, platinum, electrodes are used. If you do that, you’ll get a 1:2 ratio by volume of oxygen to hydrogen, thus proving water’s formula (H2O) as well.

So there we have it: water is a compound, and not an element. And if you’d like to amuse everyone around the Christmas dinner table, you can prove it with a 9V battery and some drawing pins. Just don’t nick the battery out of your little brother’s favourite toy, okay? (Or, if you do, don’t tell him it was my idea.)


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The Chronicles of the Chronicle Flask: 2017

We’ve made it! Not only to 2018 (which was starting to look doubtful earlier in the year), but also to the Chronicle Flask’s 100th post. Which doesn’t seem that many, really, but since posts on here frequently run to 1500 words, that adds up to a rather more impressive-sounding 150,000 words or so. I mean, that’s like… half a Brandon Sanderson novel. Oh.

Anyway, it’s time for a yearly round-up. Here goes!

Last January I began with a post about acrylamide. We’d all been enjoying lots of lovely crispy food over Christmas; it was time to tell us about the terrible dangers of such reckless indulgence. The newspapers were covered with pictures of delicious-looking chips, toast and roast potatoes alongside scary headlines such as:  “Crunchy toast could give you cancer, FSA warns”. The truth was not quite so dramatic. Acrylamide does form when foods are cooked to crispiness, and it is potentially harmful, but the quantities which form in food are tiny, and very unlikely to cause you any serious harm unless you literally live on nothing but burnt toast. The FSA (Food Standards Agency) hadn’t significantly revised their guidelines, it turned out, but were in fact only suggesting that the food industry should be mindful of acrylamide levels in food and seek to reduce them as much as possible. That wouldn’t have made for quite such a good “your food is going to killllll you!” story though, I suppose.

In February the spikey topic of vaccination came up. Again. Vaccines are awesome. They protect us from deadly diseases. No, I don’t want to hear any nonsense about “Big Pharma“, and I definitely don’t want to hear how “natural immunity” is better. It’s not. At best, it might provide a similar level of protection (but not in every case), but it comes with having to suffer through a horrible, dangerous disease, whereas vaccination doesn’t. It ought to be a no-brainer. Just vaccinate your kids. And yourself.

It was Red Nose Day in the UK in March, which brought some chemistry jokes. Turns out all the best ones aren’t gone, after all. Did you hear about the PhD student who accidentally cooled herself to absolute zero? She’s 0K now.

April brought a post which ought to have been an April Fool’s joke, but wasn’t. Sceptics often point out that homeopathy is just sugar and water, but the trouble is, sometimes, it’s not. There’s virtually no regulation of homeopathy. As far as I’ve been able to establish, no one tests homeopathic products; no one checks the dilutions. Since a lot of the starting materials are dangerously toxic substances such as arsenic, belladona, lead and hemlock, this ought to worry people more than it does. There has been more than one accidental poisoning (perhaps most shockingly, one involving baby teething products). It really is time this stuff was banned, maybe 2018 will be the year.

In May I turned to something which was to become a bit of a theme for 2017: alkaline water. It’s not so much that it doesn’t do anything (although it really doesn’t), more the fact that someone is charging a premium for a product which you could literally make yourself for pennies. It’s only a matter of dissolving a pinch of baking soda (sodium bicarbonate) in some water.

June brought a selection of periodic tables because, well, why not? This is a chemistry blog, after all! And now we’ve finally filled up period seven they do have a rather elegant completness. 2019, by the way, has just been announced as the International Year of the Periodic Table of Chemical Elements, to coincide with IUPAC’s 100th anniversary and the 150th anniversary of Mendeelev’s discovery of periodicity (his presentation, The Dependence Between the Properties of of the Atomic Weights of the Elements, was made on 6th March 1869). Looks like 2019 will be an exciting year for chemists!

In July it was back to the nonsense of alkaline diets again, when Robert O. Young was finally sentenced to 3 years, 8 months in custody for conning vulnerable cancer patients into giving him large sums of money for ineffective and dangerous treatments. Good. Moving on.

August brought me back to a post that I’d actually started earlier in the year when I went to a March for Science event in April. It was all about slime, and August seemed like a good time to finally finish it, with the school holidays in full swing – what could be more fun on a rainy day at home than making slime? Slime was a bit of a 2017 craze, and there have been a few stories featuring children with severely irritated skin. But is this likely to be caused by borax? Not really. Turns out it’s actually very safe. Laundry detergents in general, not so much. In short, if you want to make slime the traditional way with PVA glue and borax, fill your boots. (Not really – your parents will be uninpressed.)

In September it was back to quackery: black salve. A nasty, corrosive concoction which is sold as a cancer cure. It won’t cure your cancer. It will burn a nasty great big hole in your skin. Do not mess with this stuff.

October carried on in a similar vein, literally. This time with a piece about naturopaths recommending hydrogen peroxide IVs as a treatment for lots of things, not least – you guessed it – cancer. Yes, hydrogen peroxide. The stuff you used to bleach hair. Intraveneously. Argh.

The puking pumpkin!

The end of the month featured a far better use for hydrogen peroxide, that of the puking pumpkin. Definitely one to roll out if, for any reason, you ever find yourself having to demonstrate catalysis.

November brought us, somewhat unseasonally, to tomatoes. Where is the best place to store them? Fridge or windowsill? Turns out the answer involves more chemistry than you might have imagined.

And then, finally, December. Looking for a last-minute Christmas gift? Why not buy a case of blk water? I mean, other than it’s an exorbitantly priced bottle of mysterious black stuff which doesn’t do any of the things it claims to do, and might actually get its colour from coal deposits, that is.

And that, dear friends and followers, is it for 2017! Happy New Year! Remember to be sceptical when the inevitable “deadly food” story appears in a few weeks….


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Alkaline water: if you like it, why not make your own?

Me* reading the comments section on the Amazing Alkaline Lemons post (*not actually me)

Alkaline water seems to be a trend at the moment. Not quite so much in the UK, yet, but more so in the US where it appears you can buy nicely-packaged bottles with the numbers like 8 and 9.5 printed in large, blue letters on their sides.

It’s rather inexplicable, because drinking slightly alkaline water does literally NOTHING for your health. You have a stomach full of approximately 1 M hydrochloric acid (and some other stuff) which has an acidic pH of somewhere between 1.5 and 3.5. This is entirely natural and normal – it’s there to kill any bugs that might be present in your food.

Chugging expensive water with an alkaline pH of around 9 will neutralise a bit of that stomach acid (bringing the pH closer to a neutral value of 7), and that’s all it will do. A stronger effect could be achieved with an antacid tablet (why isn’t it antiacid? I’ve never understood that) costing around 5p. Either way, the effect is temporary: your stomach wall contains special cells which secrete hydrochloric acid. All you’re doing by drinking or eating alkaline substances is keeping them busy.

(By the way, I’m not recommending popping antacids like sweeties – it could make you ill with something called milk-alkali syndrome, which can lead to kidney failure.)

Recently, a video did the rounds of a woman testing various bottled waters, declaring the ones with slightly acidic pHs to be “trash” and expressing surprise that several brands, including Evian, were pH neutral. The horror. (For anyone unsure, we EXPECT water to have a neutral pH.)

Such tests are ridiculous for lots of reasons, not least because she had tiny amounts of water in little iddy-biddy cups. Who knows how long they’d been sitting around, but if it was any length of time they could well have absorbed some atmospheric carbon dioxide. Carbon dioxide is very soluble, and it forms carbonic acid when it dissolves in water which, yes, would lower the pH.

Anyway, there’s absolutely nothing harmful about drinking water containing traces of acid. It doesn’t mean the water is bad. In fact, if you use an ion exchange filter (as found in, say, Brita filter jugs) it actually replaces calcium ions in the water with hydrogen ions. For any non-chemists reading this: calcium ions are the little sods that cause your kettle to become covered in white scale (I’m simplifying a bit). Hydrogen ions make things acidic. In short, less calcium ions means less descaling, but the slight increase in hydrogen ions means a lower pH.

So, filtered water from such jugs tends to be slightly acidic. Brita don’t advertise this fact heavily, funnily enough, but it’s true. As it happens, I own such a filter, because I live in an area where the water is so hard you can practically use it to write on blackboards. After I bought my third kettle, second coffee machine and bazillionth bottle of descaler, I decided it would be cheaper to use filtered water.

I also have universal indicator strips, because the internet is awesome (when I was a kid you couldn’t, easily, get this stuff without buying a full chemistry set or, ahem, knowing someone who knew someone – now three clicks and it’s yours in under 48 hours).

The pH of water that’s been through a (modern) ion-exchange filter tends to be slightly acidic.

The water in the glass was filtered using my Brita water filter and tested immediately. You can see it has a pH of about 5. The water straight from the tap, for reference, has a pH of about 7 (see the image below, left-hand glass).

The woman in the YouTube video would be throwing her Brita in the trash right now and jumping up and down on it.

So, alkaline water is pretty pointless from a health point of view (and don’t even start on the whole alkaline diet thing) but, what if you LIKE it?

Stranger things have happened. People acquire tastes for things. I’m happy to accept that some people might actually like the taste of water with a slightly alkaline pH. And if that’s you, do you need to spend many pounds/dollars/insert-currency-of-choice-here on expensive bottled water with an alkaline pH?

Even more outlandishly, is it worth spending £1799.00 on an “AlkaViva Vesta H2 Water Ionizer” to produce water with a pH of 9.5? (This gizmo also claims to somehow put “molecular hydrogen” into your water, and I suppose it might, but only very temporarily: unlike carbon dioxide, hydrogen is very insoluble. Also, I’m a bit worried that machine might explode.)

Fear not, I am here to save your pennies! You do not need to buy special bottled water, and you DEFINITELY don’t need a machine costing £1.8k (I mean, really?) No, all you need is a tub of….

… baking soda!

Yep, good old sodium bicarbonate, also known as sodium hydrogencarbonate, bicarb, or NaHCO3. You can buy a 200 g tub for a pound or so, and that will make you litres and litres and litres of alkaline water. Best of all, it’s MADE for baking, so you know it’s food grade and therefore safe to eat (within reason, don’t eat the entire tub in one go).

All you need to do is add about a quarter of a teaspoon of aforementioned baking soda to a large glass of water and stir. It dissolves fairly easily. And that’s it – alkaline water for pennies!

Me* unconvinced by the flavour of alkaline water (*actually me).

Fair warning, if you drink a lot of this it might give you a bit of gas: once the bicarb hits your stomach acid it will react to form carbon dioxide – but it’s unlikely to be worse than drinking a fizzy drink. It also contains sodium, so if you’ve been told to watch your sodium intake, don’t do this.

If I had fewer scruples I’d set up shop selling “dehydrated alkaline water, just add water”.

Sigh. I’ll never be rich.


Like the Chronicle Flask’s Facebook page for regular updates, or follow @chronicleflask on Twitter. All content is © Kat Day 2017. You may share or link to anything here, including the images, but you must reference this site if you do.


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