Tag Archives: teaching

Combatting Chemophobia With Wine

Ava Winery composes fine vintage wines molecule by molecule in the lab
Ava Winery composes fine vintage wines molecule by molecule in the lab

The wines your great-grandchildren might one day drink on Mars will soon be coming to a bottle near you. Ava Winery is a San Francisco-based startup creating wines molecule by molecule, without the need for grapes or fermentation. With complete control over the chemical profile of the product, Ava’s wines can be created safely, sustainably, and affordably, joining the food technology revolution in creating the foods of the future.

galaxy-class_replicator
Ava Wines’ business model is somewhat akin to the Star Trek replicator!

For Ava, foods in the future will be scanned and printed as easily as photographs today. These digital recreations will be more than mere projections; they will be true chemical copies of the originals, capturing the same nutritional profiles, flavors, and textures of their “natural” counterparts. Our canvas will be macronutrients like starches and proteins; our pixels will be flavor molecules. Future generations won’t distinguish “natural” from “synthetic” because both will simply be considered food.

Consider ethyl hexanoate, although scary-sounding it is the very chemical that gives pineapples their characteristic smell and also fruity wines a tropical note. From pineapples, or indeed other organisms, ethyl hexanoate can be extracted much more efficiently. By sourcing more efficient producers of each of hundreds of different components, wines can be recreated as their originals.

Future generations won’t distinguish “natural” from “synthetic” because both will simply be considered food.

In fact, by eliminating the variability of natural systems as well as potential environmental contamination, this digitized future of food can increase the safety, consistency, and nutritional profile of foods. Such food products can reduce overall land and resource use and be less susceptible to climate fluctuations. Indeed this future will see significant reductions in the costs of food production as the cost of the raw ingredients shifts to more efficient sources of each molecule.

Processed with VSCO with s3 preset
100 to 300 compounds are responsible for the full flavour of a wine.

So why wine?

We knew there would be a controversial love/hate relationship with our mission to build wine molecule by molecule. To the elite who value the high-end wine experience, our molecularly identical creation of the $10,000+ bottle of 1973 Chateau Montelena will be a mockery; but to the public, the $10,000 turned $20 bottle will be a sensation. To the purists who still believe organic is the only way to eat or drink healthily, our wine will get “some knickers in knots”; but to the nonconformists, our wine will be a contemporary luxury made by contemporary technology.

In short, wine is just the beginning. Soon, Ava hopes to build more food products molecule by molecule further blurring these lines between natural vs. synthetic while simultaneously making luxury items available for all. With our groundwork, the Star Trek future of food might be closer than we thought.

Let’s add oxygen, fluorine and neon gases

Oxygen from Theodore Gray's amazing book, The Elements
Oxygen from Theodore Gray’s amazing book, The Elements

This post concludes the Periodic Table Smoothie experiment.

Recall that we’ve just finished adding one mole of nitrogen gas and created a bizarre boron polymer at the bottom of our vessel. The temperature was 350 °C and the pressure in our vessel was 891 kPa.

Today, we’re going to add 1.00 mole of oxygen gas, stand back and observe.

Nothing happens.

This is disappointing news.

Many of the substances in our vessel react (more accurately, explode) in the presence of oxygen but the ignition temperature for all of those explosions to take place is at least 500 °C. The temperature of our vessel is set at just 350 °C. At this temperature, nothing would actually happen.

There’s not enough activation energy to break bonds in the reactant particles in order to get the reaction started. We call this activation energy (EA) in chemistry. If we were to add a source of excessive heat (e.g. a matchstick), the vessel would explode.

Should we heat up the vessel to 500 °C and blow up the experiment right here?

If we did, the following reactions would happen:

image115
image117
image119
image121
image123
image125
image127
image129

Enough of these reactions – particularly the first three – are sufficiently exothermic to trigger a chain reaction – at least up to the reaction of oxygen with beryllium carbide. The vessel would bang, explode, and shatter. The helium would float away, dangerous lithium amide would fly out sideways, and polyborazine powder, whatever that is, would land on the floor.

Let’s not ignite our experiment – not yet.

Conclusion after adding 1.00 mole of oxygen gas

Substance Amount in mol
He(g) 1.000
Be(s) 0.514
LiH(s) 0.000
Li2C2(s) 0.272
B2H6(g) 0.000
Be2C(s) 0.175
H2(g) 0.007
BeC2(s) 0.136
CH4(g) 0.009
N2(g) 0.552
NH3(g) 0.154
LiNH2(s) 0.277
polyborazine 12.194 grams

Pressure: 891 kPa (higher than before due to the addition of nitrogen gas)
Temperature: 350 °C (vessel is still being maintained at constant temperature)

Oxygen was relatively uneventful. Let’s add fluorine and see what happens.

Let’s add fluorine gas

elements110009
Elements by Theodore Gray

The following three reactions would all occur as 1.00 mole of fluorine gas is added:

image133
image135
image131

These two products are quite interesting:

  • HF, hydrogen fluoride, an aqueous solution of which was used by Breaking Bad’s Walter White to dissolve evidence (his victims)
  • NF3, nitrogen trifluoride, is used as an etching agent when making printed circuit boards (PCBs)

Let’s add neon gas

elements110010
Elements by Theodore Gray

When 1.00 mole of neon gas is added, the total pressure inside the vessel increases but no reaction occurs. The concentrations of all the other gases present are unaffected.

The End

That concludes our Periodic Table Smoothie experiment. The most interesting conclusion was the discovery of polyborazine, the bizarre solid that collected at the bottom of the vessel.

Also of interest was how easily we created ammonia, one of the simplest of biological compounds, just by mixing elements together. Could the compounds necessary for life be so easy to create that their existence is an inevitable consequence of the Big Bang? Is life inevitable? If the Big Bang were to happen all over again, would life occur? And would it look any different?

Possibly not.

We Lied To You

Click to download the book
click-here

This book contains 50 lies taught in the VCE Chemistry course.

These lies include well-meaning simplifications of the truth, mistakes in the textbook, and, in a few extreme cases, blatant falsehoods.

This book isn’t a criticism of the VCE Chemistry course at all. In fact, I just want to highlight the sheer complexity of Chemistry and the need to make sweeping generalisations at every level so it can be comprehensible to our students. This is a legitimate practice called constructivism in pedagogical circles. (Look that up.)

Many of these ‘lies’ taught at VCE level will be debunked by your first-year chemistry lecturers at university.

Here’s a preview of some of the lies mentioned in the book. Check out all 50 by clicking the download link at the bottom of the page.


lie-2


lie-15


lie-25


we-lied-to-you-cover-lightbulbs

click-here


Pre-order my second book “We Lied To You” here

Pre-order here
Pre-order here

The content you’re learning now is probably not as true as it seems. Chemistry is a set of models that explain the macro level sometimes at the expense of detail. The more you study Chemistry, the more precise these models become, and they’ll gradually enlighten you with a newfound clarity about the inner workings of our universe. It’s profound.

Rules taught as ‘true’ usually work 90% of the time in this subject. Chemistry has rules, exceptions, exceptions to exceptions, and exceptions to those – you’ll need to peel pack these layers of rules and exceptions like an onion until you reach the core, where you’ll find Physics and Specialist Maths.

Enjoy this book. I hope it emboldens you to question everything you’re told, and encourages you to read beyond the courses you’re taught in school.

Pre-order the FREE e-book by filling in the form here.

Get my latest book here: Common VCE Chemistry Mistakes… and how to avoid them

Common VCE Chemistry Mistakes COVER.jpg

This book is a collection of common mistakes in VCE Chemistry and how to avoid them.

It comes from years of marking student SACs and exam papers, and from reading Examination Reports from the VCAA as well.

It’s free of charge, very informative, and very concise.

Click here to download the FREE book.

Redox Rules

Click to download REDOX RULES posters for VCE Chemistry
Click to download REDOX RULES posters for VCE Chemistry

What’s redox? We never learned that!

Yes, you did. I use the term “redox” to refer to all of the following chapters in Heinemann Chemistry 2, which you will have learned at the end of Term 3 (September).

  • Chapter 26: Redox (revision of Year 11)
  • Chapter 27: Galvanic Cells
  • Chapter 28: Electrolytic Cells

Don’t underestimate redox

The VCAA has consistently used redox to discriminate which schools and students have the self-discipline required to keep studying at the end of the year. Studies show that redox is taught at a time when student motivation is at its minimum: energy levels are low, emotions are high, and graduation is just over the horizon. Many schools and students gloss over these topics because they’re running out of time, any many students think they’ve grasped the topic – when they’ve actually grasped misconceptions instead.

VCAA VCE Chemistry how difficult is each topic
Notice how chapters 26, 27 and 28 are consistently the most difficult and the most frequently askedClick to download PDF version

Here are some popular redox lies (misconceptions)

LIE #1: The polarities switch during recharge
Nope. The polarities never switch. It’s the labels of ‘anode’ and ‘cathode’ that switch because the electrons are flowing the other way through the external circuit. Polarity is permanent.

LIE #2: Hydrogen fuel cells don’t emit any greenhouse gases
Wrong. They emit H2O, which is a powerful greenhouse gas. If you don’t believe that the VCAA can be this pedantic, think again. Read their 2015 Examiners Report here.

LIE #3: Each mole of electrons forms 1 mol Ag, 2 mol Cu or 3 mol Al in a cell
Wrong again. If you look at the half-equations, you’ll see that each mole of electrons actually forms 1 mol Ag, 12 mol Cu or 13 mol Al. That’s why I teach “1, 12 and 13 moles” instead of the typical “1, 2, 3 moles” rule.

LIE #4: Temperature increases the rate of reaction in electroplating
Wrong! Remember that Faraday’s first law states that m ∝ Q. Because Q = I×t, only those two things – current and time – can affect the mass deposited at the cathode.

LIE #5: Electrons always leave the anode and go towards the cathode
Wrong again. Electrons go RACO: to see what that means, download the posters above. This question appears in recent versions of Chemistry Checkpoints. Give it a try.

LIE #6: The cathode is always positive
Ask your teacher.

LIE #7: Ions flow one way in the salt bridge
Nope. Anions always migrate to the anode; and cations always migrate to the cathode.

LIE #8: KOHES always works for balancing half-equations
KOHES only works for cells with acidic electrolytes. For cells with alkaline electrolytes, which sometimes appear in VCAA papers despite not being in the study design (see page 46 here), you’ll need to use KOHES(OH). Here’s KOHES(OH) explained:

  1. Do KOHES as normal
  2. Add the same number of OH(aq) ions to each side of the half-equation to balance out the H+(aq)
  3. Cancel and simplify. Remember that H+(aq) + OH(aq) makes H2O(l). Remember also to cancel out any remaining H2O(l).

LIE #9: I can balance an unbalanced redox equation by putting numbers in the equation
Don’t be fooled by this one! The ONLY way to balance an unbalanced redox equation successfully is to do the following:

  1. Separate it into two half equations
  2. Balance them using KOHES or KOHES(OH) as appropriate
  3. Multiply them and recombine
  4. Cancel and simplify
  5. Done!

That’s a lot of work but it’s the  only way to do it successfully. If you try to ‘cheat’ by just writing numbers (molar coefficients) in front of the reactants and products, you’ll find that the charges don’t add up, and you’ll get zero marks for the question.

LIE #10: I can break up polyatomic ions to make balancing half-equations easier
Nope! You’re only allowed to separate aqueous species in a half equation or an ionic equation. Because the Mn and O are actually bonded together in a polyatomic ion, you’ll need to write this:

  • MnO4(aq) + 8H+(aq) + 5e → Mn2+(aq) + 4H2O(l)  2/2 marks

Instead of this:

  • Mn7+(aq) + 5e → Mn2+(aq)  0/2 marks

If in doubt, keep it intact and it’ll cancel out by the end if it’s a spectator ion.

LIE #11: The two reactants that are closest together on the electrochemical series react
Not always true. Use SOC SRA instead, which is explained in the posters above. Still struggling? Ask your teacher or tutor for help.

LIE #12: Oxidants are all on the top of the electrochemical series
They’re actually on the left, and all the reductants can be found on the right side of each half equation in the electrochemical series. There is no top/bottom divide on the electrochemical series: only a left/right divide of oxidants/reductants.

Decorate your school/bedroom/hallway

Surround yourselves with truthful redox revision using these 17 free Redox posters. I’ve had these up around the whiteboard for a few weeks now – they’re a constant reminder to students that redox has many ideas that are always true.

One more tip: print and laminate an electrochemical series (available here) so you can annotate it during dozens of practice dozens without wasting paper. Good luck!

LIVE Chemophobia Session Thursday 11th August @ 2pm ET

Click to register for the free webinar
Click to register for our free webinar hosted by the American Chemical Society

What can I expect to learn?

  • What does the public think of chemistry, chemicals and chemists?
  • How prevalent is chemophobia?
  • How did we evolve the propensity to become chemophobic?
  • Who were the first chemophobes?
  • What is a “chemical”?
  • Why have chemists’ efforts to fight chemophobia been to no avail?
  • What’s the ultimate cure for chemophobia, and who’s willing to fund it?
  • What can you do as a chemist to combat chemophobia?

Registration is open

Click the above banner to register for the free webinar.

Chemists need to speak the same language as the public

scientist-clipart-science-clip-art-school1
Chemists and the public need to be speaking the same language

Chemicals

The public uses the word ‘chemical’ to mean ‘synthetic substance’. Chemists have traditionally opposed this definition and stuck with ‘substance’ instead, responding with “everything is a chemical” in defence.

Arguing over definitions is futile and avoids the elephant in the room – that there’s been almost no public outreach to support the field of chemistry in the last few decades to counteract growing public skepticism of science (and of chemistry in particular).

Furthermore, it’s even more futile arguing over definitions when the Oxford English Dictionary provides a clear answer to this debate:

chemical (noun) – a distinct compound or substance, especially one which has been artificially prepared or purified

I ask all chemists to embrace the dictionary definition of ‘chemical’ and stop bickering with the public over definitions.

My main concern here is that if “everything is a chemical”, then it therefore follows that ‘chemophobia’ is the fear of everything, which is nonsensical. If we’re going to talk about chemophobia, we’re also going to have to accept the definition of chemical that the OED and the public have been using for a long time: that “chemical” = “artificially prepared substance”.

So what do we call non-synthetic chemicals? Try using a word with less baggage such as “molecule”, “compound”, “substance” or “element” where it’s relevant. By using these words, we avoid the natural=good/artificial=bad divide, which is the central assumption of chemophobia.

Chemophobia

‘Chemophobia’ is an irrational aversion to chemicals perceived as synthetic.

The word ‘chemophobia’ refers to a small subset of people who are not only disenfranchised by science, but who have subscribed to alternative sources of knowledge (either ancient wisdom or – sadly – Google). Many people with chemophobia are protesting against the establishment, and this is particularly evident in the anti-GMO movement. At the core of most people who oppose GMOs is a moral/political opposition to having their food supply controlled by giant corporations. No number of scientific studies concluding the safety and reliability of GMO crops will succeed in persuading them otherwise because the anti-GMO movement is founded on moral/political beliefs, not on science. By throwing science at them, we’re wasting our time.

More important than chemophobia

The Royal Society of Chemistry’s recent report on Public Perceptions of Science showed roughly a 20-60-20 range of attitudes towards chemistry.

206020.png

No matter how the RSC phrased the question, roughly 20% of the UK public who were surveyed indicated a negative attitude towards chemistry, and another 20% showed a positive attitude. The 60% in the middle felt disconnected from the subject – maybe disliked it in school – but felt neutral towards it when asked.

Chemophobia afflicts some people in the bottom 20%. They gave negative word-associations with ‘chemistry’ (e.g. ‘accidents’, ‘dangerous’ and ‘inaccessible’).That bottom 20% group is so vocal (e.g. Food Babe) that they distract chemists from the 60% in who are neutral. The ‘neutral’ crowd is a much larger audience that’s much easier to engage/persuade through outreach efforts. We should focus on talking to them.

Neil deGrasse Tyson has said in interviews that his huge TV hit show COSMOS was aimed at “people who didn’t even know they might like science”. That’s the middle 60%. Brian Cox’s amazing Wonders of the Universe was aimed at a similar audience – but chemistry has nothing similar to offer. We’re engaging those who are already interested (with academic talks and specialist journals) and we’re engaging with the bottom 20% via social media and comments on foodbabe.com… but why haven’t we started engaging the middle 60%, who gets most of their science information from TV? How many chemistry TV icons can you name? Where are the multi-channel launches of big-budget chemistry documentaries*? Chemistry is lagging far behind biology and physics in that regard.

*BBC Four’s Chemistry: A Volatile History (2010) doesn’t count – it was only three episodes long, got no further than ‘the elements’ and was presented by a PHYSICIST!

Focus on the 60% who are ‘neutral’

I ask chemists to focus on addressing the disinterested 60%. From an outreach perspective, this is much more fun and is positive rather than reactionary. By engaging those who feel neutral about chemistry, we might even empower enough of the public to fight chemophobia (online, at least) by themselves – without our direct intervention.

I urge chemists to tell the public what you do in simple terms. Describe your work to the public. Tweet about it. Participate in your university/faculty’s YouTube videos by explaining your work and its relevance. Offer advice as a science correspondent for local media outlets (many universities have ‘expert lines’ – get involved). Give your ‘talk’ at local schools – it make a HUGE difference to students’ perceptions of science. Devote 5% of your working time to doing outreach. As a teacher, I’m practically doing it full-time.

Plus, we urgently need a chemistry TV hero. Could someone do that, too, please?

Registration is open!

live-webinar-pic

About the webinar

James Kennedy will explore the rise of chemophobia, an irrational fear of compounds perceived as ‘synthetic’, and the damage it can cause in this interactive webinar. We’ll examine its evolutionary roots, the factors keeping it alive today and how to fight chemophobia successfully.

What You Will Learn

  • Origins of chemophobia as an irrational psychological quirk
  • Chemistry teachers, Walter White, materialism and advertisements are all fuelling chemophobia today
  • Fighting chemophobia needs to be positive, respectful, multifaceted, and good for consumers

Webinar Details

  • Date: Thursday, August 11, 2016 @ 2-3pm ET
  • Fee: Free to Attend
  • Download Slides: Available Day of Broadcast

Register your attendance here.

slide
Slide from the lecture. Click to register to attend.

ASAP Science Video: This is NOT NATURAL

this is not natural
Click to watch AsapSCIENCE’s video on YouTube

AsapSCIENCE has made an awesome video called This is NOT NATURAL based on the work I’ve been doing on this site. Watch the video and read the comments thread for some insight into the discussion (and misinformation) that spreads online regarding ‘natural’ and ‘healthy’ products.

One of the most upvoted comments is actually a thinly-veiled advertisement for a book called “The Coconut Oil Secret: Why this tropical treasure is nature’s #1 healing superfood”. Click through to their product page and you’ll see why the natural/organic sector needs more regulation, and why consumers need to be better-informed.

Check out the video below, or click here to visit the comments thread on YouTube.

‘Chemophobia’ is irrational, harmful – and hard to break

Chemophobia lab.jpg
Kiran Foster/Flickr

We all feel a profound connection with the natural world. E O Wilson called this sensation biophilia: ‘the urge to affiliate with other forms of life’. That sense of connection brings great emotional satisfaction. It can decrease levels of anger, anxiety and pain. It has undoubtedly helped our species to survive, since we are fundamentally dependent on our surrounding environment and ecosystem. But lately, biophilia has spawned an extreme variant: chemophobia, a reflexive rejection of modern synthetic chemicals.

Continue reading this article on AEON IDEAS…

Let’s add carbon (graphite) powder

elements110006
‘Carbon’ page from Theodore Gray’s amazing book: The Elements

Today, we’re going to add 1.00 mole of carbon to our vessel. After adding boron last week, we left our vessel locked at 350 °C and with a pressure of 638 kPa. These reactions are taking place at 350 °C and constant volume (exactly 10 litres). Pressure inside the vessel will therefore change over time.

Allotropes of carbon

Carbon has various allotropes (structural arrangements of an element). Diamond is extremely strong and highly unreactive, while graphite is soft and brittle. The differences are all due to the type of bonding between carbon atoms. In diamond, carbon atoms are bonded by four strong covalent bonds with the surrounding atoms in a strong, hard three-dimensional ‘network lattice’. Graphite owes its softness and brittleness to the fact that its carbon atoms are bonded by only three strong covalent bonds in a two-dimensional ‘layer lattice’. Individual layers are very strong, but the layers can be separated by just the slightest disturbance. Touching graphite lightly onto paper will remove layers of carbon atoms and place them onto the page (such as in a pencil). Using a diamond the same way would likely tear the paper instead.

For this reason, I’m going to put graphite into the vessel instead of diamond. Diamond is so strong and inert that it’s unlikely to do any interesting chemistry in our experiment. Graphite, on the other hand, will.

The following seven chemical reactions will take place after adding carbon (graphite) powder

As soon as the carbon powder enters the vessel, it will begin to react with the following three species as follows:

image067
image071
image075

The ethyne produced in the third reaction will then react with any lithium and beryllium remaining in the vessel as follows:

image079
image081

The hydrogen gas produced by the above two reactions will then react with lithium and carbon (if there’s any left) as follows:

image083
image085

These reactions have the potential to all occur at the same time. Tracking them properly would require calculus and lots of kinetics data including the activation energy of each reaction and the rate constant for each equation. Quick searches on the National Chemical Kinetics Database yields no results for most of these equations, which means we won’t be able to use a computer model to calculate exact quantities of each product. Instead, I’m going to run a computer simulation using Excel that makes the following three assumptions:

  • all these reactions occur at the same rate;
  • all these reactions are first-order with respect to the limiting reagent;
  • all these reactions are zeroth-order with respect to reagents in excess.

The results will be a close approximation of reality – they’ll be as close to reality as we can get with the data that’s available.

Here are the results of the simulation

Here’s a graph of the simulation running for 24 steps. Exactly one mole of carbon powder is added at step 5.

Periodic Table Smoothie - Let's Add Carbon Carbon quickly reacts to form lithium carbide, beryllium carbide and two organic molecules: methane and ethyne
Carbon quickly reacts to form lithium carbide, beryllium carbide and two organic molecules: methane and ethyne

Summary of results

The results are incredible! We’ve made ethyne and methane, both of which have the potential to do some really interesting chemistry later on. I’m hoping that we can make some more complex organic molecules after nitrogen and oxygen are added – maybe even aminoethane – let’s see.

Hydrogen has also re-formed. I’m hoping that this gas lingers for long enough to react with our next element, nitrogen: we might end up making ammonia, NH3(g).

You may have noticed that I removed the “boron-lithium system” from the vessel. The 0.178 moles we created are now stored separately and will not be allowed to react any further. With such little literature about the reactivity of B3Li, it’s impossible to predict what compounds it’ll form later on. B3Li is so rare that doesn’t even have a Wikipedia page.

Pressure in the vessel increases to 718 kPa after carbon is added
Pressure in the vessel increases to 718 kPa after carbon is added
mass of sludge in periodic table smoothie after adding carbon.png
Mass of sludge in the vessel changes after adding carbon

Here’s what’s present in the vessel after adding carbon

Substance Moles present after 500 ‘steps’
He(g) 1.00000
Be(s) 0.51435
LiH(s) 0.27670
Li2C2(s) 0.27165
B2H6(g) 0.23300
Be2C(s) 0.17470
H2(g) 0.14267
BeC2(s) 0.13625
CH4(g) 0.00949

We also have 0.178 moles of B3Li stored separately in another vessel.

Next week, we’ll add nitrogen and see what happens.

Let’s add boron powder

elements110005
‘Boron’ page from Theodore Gray’s book, The Elements

Boron is a metalloid: an intermediate between the metals and non-metals. It exists in many polymorphs (different crystal lattice structures), some of which exhibit more metallic character than others. Metallic boron is non-toxic, extremely hard and has a very high melting point: only 11 elements have a higher melting point than boron.

British scientist Sir Humphrey Davy described boron thus:

“[Boron is] of the darkest shades of olive. It is opake[sic], very friable, and its powder does not scratch glass. If heated in the atmosphere, it takes fire at a temperature below the boiling point of olive oil, and burns with a red light and with scintillations like charcoal” – Sir Humphrey Davy in 1809

Initial condition

Before we add the 1.00 mol of boron into our reaction vessel, we need to recall what’s already in there from our experiments so far:

  • H2(g): 0.70 mol
  • He(g): 1.00 mol
  • Li(s): 0.40 mol
  • LiH(s): 0.60 mol
  • Be(s): 1.00 mol

The temperature of our vessel is 99 °C and the pressure of the gaseous phase is 525.5 kPa.

Now, let’s add our 1.00 mol of boron powder.

Which reactions take place?

Boron reacts with hydrogen gas to produce a colourless gas called borane, BH3(g), according to the following equation[1]:

image034.png

Boron also reacts with lithium in very complex ways. If we heat the vessel up to 350 °C, we’d expect to see the formation of a boron-lithium system with chemical formula B3Li according to this equation[2]:

image030.png

Notice that now we’ve heated up our vessel to 350 °C to allow this reaction to happen, the lithium at the bottom of the vessel has melted.

Boron reacts with lithium hydride as well, but only at temperatures around 688 °C. With our vessel’s temperature set at 350 °C, we won’t observe this particular reaction in our experiment.[3]

Some allotropes of boron – in particular, the alpha allotrope that was discovered in 1958 – is capable of reacting with beryllium to form BeB12. Because we’re using beryllium powder, which has semi-random  symmetry, we won’t see any BeB12 forming in our vessel. Alpha-boron only exists at pressures higher than around 3500 kPa. At our moderate pressure of only 525.5 kPa, powdered (semi-random) boron will prevail and no BeB12 will form.[4]

For simplicity’s sake, let’s assume that the two reactions above take place with equal preference.

Boron powder reacts with hydrogen gas

Let’s do an ice table to find out how much borane we make.

image034.png

A quick n/ratio calculation shows us that the hydrogen gas is limiting in this reaction:

image035
image037
image039

We can expect all of the hydrogen gas to react with the boron powder.

units are mol 2 B 3 H2 2 BH3
I 0.50 0.70 0
C -0.466 -0.70 +0.466
E 0.0333 0 0.466

Borane is very unstable as BH3, and it would probably dimerise into B2H6(g). This is still a gas at 350 °C and is much more stable than BH3. For the rest of this experiment we’ll assume that our 0.466 mol of BH3 has dimerised completely into 0.233 mol of B2H6.

Boron powder reacts with lithium

With the molar ratios present in our vessel, at 350 °C, we’d expect to witness the formation of a boron-lithium system, with chemical formula B3Li.

image030.png

A quick n/ratio calculation shows that in this reaction, the boron powder is limiting.

image041
image043
image045

All of the remaining boron therefore reacts with lithium. To calculate exactly how much B3Li we’ve created, let’s do another ice table:

units are mol 3 B Li B3Li
I 0.533 0.40 0
C -0.533 -0.178 +0.178
E 0 0.222 0.178

What’s in our vessel after adding boron?

We have the following gas mixture in our vessel:

Helium gas, He(g): 1.00 mol

Helium is an inert noble gas that will probably remain in the vessel until the end of the experiment. It’s used in party balloons.

Borane gas, B2H6(g): 0.233 mol

We made this today. Borane is used in the synthesis of organic chemicals via a process called hydroboration. An example of hydroboration is shown below.

250px-hydroboration-oxidation_of_1-methyl-cyclohex-1-ene

At the bottom of the vessel, there’s a sludge, which contains the following liquids and solids:

Molten lithium, Li(l): 0.22 mol

Lithium is used in the production of ceramics, batteries, grease, pharmaceuticals and many other applications. We’ve got 0.22 moles of lithium, which is about 1.5 grams.

Beryllium powder, Be(s): 1.00 mol

Beryllium is used as an alloying agent in producing beryllium copper, which is used in springs, electrical contacts, spot-welding electrodes, and non-sparking tools.

Lithium hydride, LiH(s): 0.60 mol

Lithium hydride is used in shielding nuclear reactors and also has the potential to store hydrogen gas in vehicles. Lithium hydride is highly reactive with water.

Boron-lithium system, B3Li(s): 0.178 mol

We made this today… but what is it? Not much is known about this compound – in fact, it doesn’t even have a name other than “boron-lithium system, B3Li”. It’ll probably decompose eventually in our experiment – maybe when we alter the pressure or temperature of the vessel at some later stage. We’ll need to keep an eye on this one.

The original H2(g) and B(s) have been reacted completely in our experiment.

What’s the pressure in our vessel now?

At the end of our reaction, the temperature of our vessel is still set at 350 °C and the pressure of the gaseous phase inside the vessel can be calculated to be a moderate 638 kPa as follows:

image002
image054
image058

*It should also be noted that some evidence exists for a reaction between LiH and BH3, forming Li(BH4). The reaction seems to take place stepwise with increasing temperature. A quick read of this paper suggests that in our vessel, which is at 350 °C, any Li(BH4) formed would actually break back down into boron powder and hydrogen gas, which would in turn react with each other and with lithium metal to form BH3 and LiH again. The net result would be a negligible net gain of LiH and a negligible net loss of boron powder. We will continue calculating this Periodic Table Smoothie under the assumption that if any Li(BH4) forms, it breaks down before we add the next element, and the overall effect on our system is negligible.

**Li(BH4) is an interesting compound: it’s been touted as a potential means of storing hydrogen gas in vehicles – it’s safer and releases hydrogen more readily than LiH, which was mentioned above.[5]

Next week, we’ll add element number 6, carbon, and see what happens.

References

  1. “Borane”. Wikipedia. N.p., 2016. Web. 14 Apr. 2016.
  2. Okamoto, H. “The B-Li (Boron-Lithium) System”. Bulletin of Alloy Phase Diagrams 10.3 (1989): 230-232.
  3. Matkovich, V. I. Boron And Refractory Borides. Berlin: Springer-Verlag, 1977. Print.
  4. Gaulé, G. K. Boron, Volume 2: Preparation, Properties And Applications. New York: Plenum Press, 1965. Print.
  5. Saldan, Ivan. “A Prospect For Libh4 As On-Board Hydrogen Storage”. Open Chemistry 9.5 (2011): n. pag. Web.

Let’s add beryllium powder

elements110004
‘Beryllium’ page from Theodore Gray’s book, The Elements

Initial condition

  • H2(g): 0.70 mol
  • He(g): 1.00 mol
  • Li(s): 0.40 mol (still solid: it melts at 180.5 degrees)
  • LiH(s): 0.60 mol
  • Pressure = 525.5 kPa
  • Temperature = 99°C

No reactions!

Beryllium doesn’t react with any of the things in the vessel: H2(g), He(g), Li(s) or LiH(s). My one mole of beryllium powder (which would cost me over $70) would just sit at the bottom of the vessel doing nothing.

With not much else to write about in the Periodic Table Smoothie this week, it might be a good idea to calculate how much this Periodic Table Smoothie would have cost in real life.

Element Cost per kg[1]  Molar mass  Cost per mole
H2  $              4.00 2  $       0.008
He  $            52.00 4  $       0.21
Li  $          270.00 6.941  $       1.87
Be  $      7,840.00 9.01  $    70.64
B (next week)  $    11,140.00 10.811  $  120.43
TOTAL cost of 1.00 mol of each of the first five elements  $        193.16

Conclusion

The addition of beryllium was highly uneventful. The vessel still contains the following:

  • H2(g): 0.70 mol
  • He(g): 1.00 mol
  • Li(s): 0.40 mol (still solid: it melts at 180.5 degrees)
  • LiH(s): 0.60 mol
  • Pressure = 525.5 kPa
  • Temperature = 99°C

We’ll add boron next week and see what happens.

What if we put 200 g ice into 1.00 L hot water?

Ice + water --> ice water
How much of a chill will these ice cubes give to a bucket of hot water?
Today, we’re going to answer the following question:

When 200 grams of ice is added to a bucket containing 1.00 litre of hot water, what’s the final temperature of the water?

To answer the question, we’re going to need to make some assumptions. We’ll take 1.000 litre of pure water at 80.00°C and add 200.0 g of ice (at -10.00°C) to it. What’s the final temperature of the water?

Part 1: Heat transfer method

The following equation can calculate the temperature at thermal equilibrium of any number of objects in thermal contact.

image001.png

I love this equation because it’s several lines of maths shorter than the version taught in school. With this equation, you don’t even need to convert the temperatures into kelvin. Celsius works just fine.

Let’s set up the equation so that the addition series contains the variables in the question.

image003.png

Now, let’s substitute the gives values into the equation. The specific heat capacity of water is 4200 J kg-1 K-1, and that of ice is 2100 J kg-1 K-1.

image005.png
image007
image009
image011

Great! Adding 200.0 g of ice to 1.000 L of water decreases the temperature from 80.00°C to 71.80°C.

But we’ve forgotten something. The ice will melt as soon as it hits the hot water. Since melting is an endothermic process, heat energy from the water will actually be absorbed, thus reducing the final temperature even further.

Part 2: Let’s take into account the fact that the ice melts!

Remember our formula from part 1.

image009

The amount of energy required to melt ice can be calculated using the latent heat equation:

image013
image015
image017

Removing that amount of heat energy from the system results in the following equation:

image019.png
image021.png

Great! Now, we’ve calculated that the final temperature of the water would be 57.36°C after the addition of the ice. That’s equal to 330.5 kelvin, which will be useful later.

However, we’ve forgotten to take something else into account: how much heat will be lost as radiation from the surface of the bucket?

Part 3: What’s the rate of heat loss from the bucket by radiation?

The rate of heat lost by radiation can be calculated by using the Stefan-Boltzmann equation, below.

image023.png

P is the rate at which heat energy is radiated from the surface of the bucket in watts. Emissivity, e, of water is 0.95, and the surface area, A, should be around 0.0707 m2 for a one-litre bucket. Calculation of A is shown below. Assuming that the radius of the surface of the bucket is 6cm:

image025
image027
image029

Plugging that value into the equation, we can find P. We’ll assume that the experiment is being conducted at room temperature and the temperature of the surroundings is 20.00°C (29.03 K).

image023
image031
image033

This means that 2.928 joules of energy are emitted from the surface of the bucket every second. Ten minutes later, the bucket would have lost 1756.8 joules of energy due to radiation from the surface. But what about emission of radiation from the sides of the bucket?

Let’s say that our bucket is made from highly polished aluminium (which has emissivity 0.035) and it holds exactly 1.2 litres of water. We need to calculate the dimensions of the bucket.

Assuming it has straight sides (i.e. it’s a cylinder), the bucket had volume equal to the following formula:

image035
image037
image039
image041

The surface area of our bucket (excluding the open surface at the top) is:

image043
image045
image047

The rate of energy radiation from the sides would therefore be:

image023
image049
image051

It’s interesting to note how very little radiation is emitted from the shiny aluminium bucket, while lots more radiation is emitted from the surface of the water. This is because relatively ‘dark’ water has a much higher emissivity than shiny aluminium. Total emission from the bucket is therefore:

image053.png

After ten minutes, the bucket would have lost the following amount of energy:

image055
image057
image059

Let’s factor this amount of energy loss into our final temperature equation.

image061
image063

Not much energy is lost via radiation! Finally, let’s find the peak wavelength of the radiation emitted by the object using Wien’s law.

Part 4: What’s the wavelength of the radiation being emitted by the bucket?

Here’s Wien’s law from Unit 1 Physics…

image065
image067
image069

The radiation emitted from the resulting bucket of water lies firmly in the infra-red part of the electromagnetic spectrum. The bucket would be clearly visible on an infra-red camera!

Next week, we’ll begin a new a Chemistry-themed project called Periodic Table Smoothie. More next week.

Subscribe to Chad Jones’ New Chemistry Podcast

collapsed wavefunction logo
New podcast ‘Chemical Dependence’ is hosted at The Collapsed Wavefunction

I first came across Chad Jones when I did an interview with him on The Collapsed Wavefunction back in 2013. We discussed ingredient labelling, chemophobia and my motivations for making the Ingredients of an All-Natural Banana poster series.

Chad Jones works at Intel Corp. in Utah, USA. He’s the founder and chief science writer for The Collapsed Wavefunction, a science advocacy podcast featuring episodes on science instruction, science in popular culture, and current science news items.

In 2016, Chad’s launched his latest venture in chemistry outreach with a fantastic new podcast called Chemical Dependence. In each of the podcast’s punchy, 5-minute episodes, Chad explores interesting chemical compounds and how they’re used in society. The podcast is a great source of interesting facts to liven up any chemistry lesson. All Chemistry teachers should subscribe!

He’s even teamed up with Andy Brunning from Compound Interest for his latest episode on pipeline. Check it out here.

Check out all the episodes and subscribe to the podcast on iTunes here. Support the podcast via Patreon here.