Learning chemistry more pointless than ever, experts agree

Amorous Atoms

Chemistry lessons are to be scrapped following the discovery that everything is due to something you’ll learn about later.
The subject had been hanging by the thread of a single, credible explanation for a chemical phenomenon.
But that all changed when researchers overturned the classic reason used to explain the fact that oil and water don’t mix – already complicated enough to send even the geekiest swots reaching surreptitiously for their smart phones.
Instead of learning that water molecules are more attracted to each other than to oil molecules, students will now be told simply that it’s “thermodynamically unfavourable, which is something you’ll learn about later.”
Thermodynamic caveats have increasingly been used to justify chemical happenings, including the supposed obsession of atoms for gaining full outer shells.
“The really disappointing thing is when teachers encourage students to believe that atoms ‘want’ to gain full outer shells of electrons,” said Professor Raymond Travis. “This kind of anthropomorphism is really unsatisfactory.”
But teacher Reggie Wilcox countered: “Well he can get stuffed! How many year 10s does he have to teach about atomic theory?? The lynch pin of school chemistry is that atoms are happy when they get full outer shells. If you take that away, the whole subject will collapse on itself.”
In response ministers have voted to axe the subject.
The secretary of state for education Tarquin Tweets-Wildly said: “We make them learn all of this jibber jabber but it turns out that everything in chemistry can only be understood when you’ve learned more chemistry. This paradoxical pickle is precisely the kind of thing that might make students start to think for themselves, which is to be avoided at all costs. Clearly it’s vital that students are still made to learn things that they despise, so we’re just going to make them do more maths lessons.”

Spoofs Aside

The serious point to this article is that everything in chemistry really does seem to be something that can only be properly understood far in the future of students’ chemical education – if they ever get there.

Today I’ve read in Eric Scerri’s blog that the idea of equating pH7 to neutrality should be abandoned. A sympathiser in the comments section noted the inadequacy of school level explanations for atomic bonding, particularly in text books. David Read at Southampton University has noted that the problem is more likely to occur when non-specialists have to teach GCSE level chemistry.

To be honest, I am a chemistry specialist, and I’m still not entirely sure what the best angle to take is. Here are a couple of chemical fallacies I’ve accidentally taught in recent years:

Oil and water do not mix because the water molecules are more attracted to each other than to oil molecules. Todd Silverstein advised back in 1998 that this erroneous explanation should be removed from text books, which may explain why I had to look beyond the text books used at my school to find this anachronism. It was a moment’s work to find it online. The thing is, the greater affinity between water molecules is relevant to the explanation, otherwise their subsequent formation of clathrates wouldn’t make the process entropically unfavourable.

The internet also got it wrong on the reason why salt reduces the freezing point of water. The salt particles get in the way of the water molecules, thus impairing the formation of the crystal. But as someone else pointed out (also on the internet, to its credit), the salt ions would also impair the process of water molecules detaching from the nascent ice crystal. I’d confused kinetics and thermodynamics. The thing is, I get the kinetics and thermodynamics thing, but it makes for an atrocious explanation: so class, the reason why this happens is because the laws of physics require it. Physics text books are terrible for explaining everything in terms of equations. A physics teaching colleague of mine once noted that it can be very difficult to present physics to a lay audience, because there are limits to what can be understood without the equations. Even so, there is a qualitative component to all of these phenomena, which is not always readily appreciated from physics texts.

Thermodynamic favourability cannot be appreciated until the second year of the A-level course but its treatment there is surely next on the hit list for university professors. The randomness entailed by increased entropy is a very relatable way to introduce the topic, but university level texts typically lament its inadequacy. Only then can students appreciate that the chaos typifying positive entropy changes is characteristic of the distribution of particles between energy levels in the manner that can be achieved in the most different ways.

This is nothing new. Fresh-faced A-level students are the first to point out that GCSE chemistry was nothing but a pack of lies. I don’t tell them that history will repeat itself at university – after all, so few of them will end up studying the subject at degree level. @teachingofsci published a blog article earlier stating that just 3% of the students he took on in year 7 went on to take physics at university.

Academics are telling us that these half-story or wrong-story explanations make it harder for students when they reach university level. But would it really be any easier if we tacked the addendum to every half-explained concept that the reason for this is beyond the scope of this text? Is there anything we can meaningfully teach that isn’t beyond the scope of the text??

In another forum dispute, someone picked me up for defining a chemical reaction as a phenomenon in which new bonds are created. He presented an example of a complex ion going from a 2+ to a 3+ charge without a single ligand exchange. At that time, the curriculum still required me to teach this fallacy to 11- to 14-year-old students. There are so many problems with the old physical vs chemical change section of the curriculum. Signs of a chemical reaction include: temperature change, colour change, production of gas, yet all of these can characterise physical changes. Frying an egg is a chemical reaction? Well actually, the physical change of the denaturation of the proteins plays an arguably more important role than the chemical joining of the unravelled strands. (Even then, denaturation isn’t a strictly physical phenomenon, as salt and sulphur bridges are likely cleaved.) That forum dweller bid me use the definition that a chemical reaction is a process involving the transfer of electrons between species, but of course that now complicates the teaching demand. This new idea of a chemical reaction, class, can be understood in terms of an additional, more complex new idea – the electron. Or in kid speak: “Sir, what’s an electron?”

I feel like plenty must already have been said on this subject – and I would welcome being pointed to any of it – but is it possible to get students to the university level without teaching them stuff that isn’t quite right? And once that question is answered, the follow up is: when so few of your students will actually go on to study chemistry at university, is it really the worst thing in the world to give them the closest approximation that their current level of understanding permits?

Another question is this idea that teachers are laying misconceptions that foil the efforts of university level educators. One of the great achievements of the constructionist paradigm has been the observation that learners will get hold of misconceptions all by themselves. They are firmly in place before a child’s first science lesson. These are important matters. It feels ironic that the A-level chemistry curriculum is fresh from a government-masterminded overhaul. All of these issues should have informed it, but instead we have simply been issued a new sequence in which to jump through the same hoops. The concepts can still be taught “the right way” and “the wrong way”, of course, but I don’t feel that much clearer as to which is which.

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Dig Deeper for Profitable Recyc

what links gunpowder fertiliser medicine and gold

Name the liquid: Napolean wanted it to make gunpowder. The Chinese tapped it for medicinal hormones. Alchemist Henning Brandt boiled it down in search of gold. Now researchers believe this bountiful substance could be used to produce electricity as well as fertiliser. What is this mystery substance? Urine.

In fact, a team led by researchers Pablo Ledezma and Stefano Freguia, has urged us to dig deeper when it comes to mining resources from human waste.

Schemes have already been proposed to tap energy from urine but none so far has been profitable. Now the research team, composed of Australia- and Netherlands-based scientists, has come up with a way to make the projects viable – by mining nutrients as well as producing energy.

Seldom does science present win win scenarios but that is precisely what seems to be happening. Only by wringing every last drop of recycling potential from our waste is the enterprise possible.

What the researchers have proposed is that potassium, nitrogen and phosphorous should be extracted for use as fertiliser, alongside the energy generation processes.

First of all, how can urine be used to produce energy? There are two methods. The first is to use urine as an electrolyte in a fuel cell. Chemical reactions are defined as processes in which new substances are created by the transfer of electrons between species. Fuel cells separate the reactants into two compartments that are joined by an electrical conductor. In order for the reaction to proceed, the electrons are transferred via the conductor, in which a current is hence generated.

This special case requires electrodes that are impregnated with microorganisms that catalyse the process. Other substances are required to generate electricity in significant amounts, which is one of the reasons why the process is yet to turn a profit.

The second option is to carry out electrolysis on the urine. Instead of generating electricity, a current is applied to the urine, driving various reactions including one that produces hydrogen. This gas can also be used to drive fuel cells and produces electricity much more readily.

Neither process has been profitable to date, but operators of such microbial electrochemical technologies (MET) need to be more enterprising. In addition to generating useful energy, the electrochemical units can also be used to gather ammonia for use in fertilisers.

Human excreta have been used as fertiliser for millennia. Indeed, as far as most plants are concerned, our urine provides a perfectly balanced diet. This is because the proportion of nitrogen, phosphorous and potassium in our liquid waste matches that in which the elements are drawn from the soil.

This is incredibly important because agriculture is intrinsically linked to energy consumption. The Born-Haber process, by which ammonia is produced for use in fertiliser, requires huge amounts of energy to generate high temperatures and pressures. As the global population grows, demand for fertiliser will outstrip supply, a problem which will only be aggravated by the intensifying energy crisis. As such, in order to guarantee food security, countries will need to look for new sources of fertiliser.

One barrier for the use of urine is the global migration from rural to urban areas. Once urine arrives at waste water processing plants, it is already too dilute for extraction to be viable. An alternative would be to gather urine in urban areas and transport it to the rural areas where it is required. Unfortunately, the majority of our urine is water, meaning that the cost of transporting the desired nutrients would be vastly inflated by the cost of transporting the superfluous water in which they are dissolved.

As such, the ideal solution is to process the urine locally, prior to the delivery of the mineral extract. Not only might METs become a viable means by which to produce electricity, but they could also present a convenient way by to extract the nitrogen present in the form of urea.

This can be combined with another process in which nitrogen and phosphorous are extracted by crystallisation of the compound struvite (MgNH4PO4.6H2O). This method is not effective as a standalone solution because the 1:1 stoichiometry of nitrogen and phosphorous does not reflect the balance in which the elements occur in our urine, which typically contains 5 to 10 times as much nitrogen as phosphorous.

Other barriers remain. For instance, how would the urine be collected? The authors suggest it could be gathered alongside household waste but that requires the cooperation of refuse collectors and householders, who – to say the least – might require some convincing.

Nevertheless, as finite resources dwindle and energy bills soar, it will be harder to make excuses for our squeamishness about this bountiful supply of life-sustaining elements.

A history of mining urine for valuable resources

  • The Chinese were extracting medicinal hormones from urine more than 2000 years ago
  • Napolean issued an ordinance requiring citizens to urinate on nitre beds of piled up manure and garbage, in order to produce saltpetre for use in gunpowder production.
  • The element phosphorous was actually discovered in 1669 when the alchemist Hennig Brandt boiled down bucket loads of urine in the hopes of extracting gold. The rationale appears to have been the resemblance between the colours of the precious metal and the aesthetically less appealing liquid.
  • British hiker Paul Beck and yachtsmen Mark Smith and Steven Freeman all believe that drinking their own urine ensured their survival after becoming stranded without water supplies. Questions remain as to whether or not they are right to think so.

References: Source-separated urine opens golden opportunities for microbial electrochemical technologies, Pablo Ledezma, Philipp Kuntke, Cees Buisman, Jürg Keller, Stefano Freguia http://www.sciencedirect.com/science/article/pii/S0167779915000232

The Genius of China, 3,000 years of Science, Discovery and Invention, Robert Temple, 1998, Prion Books, London

Urine: The body’s own health drink? The Independent website http://www.independent.co.uk/life-style/health-and-families/health-news/urine-the-bodys-own-health-drink-467303.html

Radar, Hula Hoops, and Playful Pigs: 67 Digestible Commentaries on the Fascinating Chemistry of Everyday Life by Joe Schwarcz, 2001, Holt Paperbacks

UK curriculum links

KS5 chemistry

Electrochemistry

Fuel Cells

Stoichiometry

KS3 and KS4 science

Energy production

Recycling

Use of fertilisers in agriculture