Category Archives: Science

The Chemistry behind the Tianjin Explosions

liu_bolin_tianjin_explosions_2016
Artwork by Liu Bolin: “Tianjin Explosions”

About the artist: Liu Bolin imbeds himself and others into the photograph, declaring their position as individuals within the catastrophic incident, thus calling viewer’s attention to the aftermath and investigation of the disaster. Through recreating the imagery of the damage and devastation caused by the explosion, the project is Liu’s attempt to reveal social issues in China, as well as to reflect on the complex relationship between the past and the present, the reality and the illusion, as well as individuality and society. Visit Liu Bolin’s gallery page here.

As a Chemistry teacher, my initial reaction to the enormous explosions at a hazardous chemicals storage facility in Tianjin, China this week was a need to find out what exploded and why. As soon as the news broke, I started following #Tianjin on Twitter and getting alerts from Google News. Here’s what I’ve learned about the Chemistry behind these two fatal blasts. We know there were several dangerous chemicals on site. We also know that firefighters were present at the facility putting out a fire before the first explosion. The second explosion was much larger than the first, with the two blasts measuring the equivalent of 3 and 21 tons of TNT, respectively. The second, larger blast was so powerful that it caused a magnitude 2.9 earthquake in the surrounding area. For a surface explosion to cause a measurable earthquake is rare.

Here’s my understanding of what happened.

Stage 1: Fire

An unknown substance caught fire inside one of the storage containers at the facility. Firefighters arrived at the scene to douse the flames with water.

Stage 2: Water touches calcium carbide, producing acetylene gas

CaC2(s) + 2H2O(l) → Ca(OH)2(s) + C2H2(g) ΔH = -127.7 kJ/mol

Calcium carbide, CaC2(s), is an unstable compound that’s used in the production of acetylene (ethyne) and also in steelmaking. When water (or moist air) touches calcium carbide, it fizzes gently, releasing acetylene gas, C2H2(g), which, when mixed appropriately with air, explodes upon ignition. The reaction above is only slightly exothermic, and the ethyne gas released is colourless and odourless: it’s possible that the firefighters didn’t even notice that the gas was being produced.

Stage 3: Flames ignite the acetylene gas, causing the first explosion

After the ethyne had mixed sufficiently with the surrounding air, one part of this explosive gas mixture was ignited by the pre-existing flames, causing the first explosion.

C2H2(g) + 5/2O2(g) → 2CO2(g) + H2O(g) ΔH = -1299 kJ/mol

Eyewitness reports have estimated this first explosion to be equivalent to 3 tons of TNT, which equates to 12.5 million kilojoules of energy. Using n = E/ΔH, we find that around 9662 moles of ethyne appears to have exploded. Using V = n×VM, we can calculate that at 25°C and 1 atm of pressure, that explosive gas would have occupied a volume of 236719 litres. Using r = (3V÷4π)1/3, we can approximate the ethyne gas to have occupied a sphere 76 metres in diameter, which is (very approximately) consistent with what we’ve seen in the video footage.

Interestingly, we can do a simple stoichiometric calculation using m = n×Mr and calculate the initial mass of calcium carbide that decomposed: 9662 × 64.1 = 619 kilograms. At a density of 2.22 g/cm3, those 619 kilograms would have occupied 279 litres in powdered form: this is about the same size as three large luggage cases.

A quick search on Chinese wholesale directory Alibaba.com shows that very few companies offer calcium carbide in such small quantities, which might help narrow down which company was responsible. Interestingly, the raw material for that first explosion was worth a mere US$400 at 2015 wholesale prices… but the consequential damage was far more costly.

Stage 4: High temperatures caused nearby ammonium nitrate to detonate at >240°C, causing the second explosion

Temperatures of over 3000°C were generated by the combustion of the ethyne in stage 3. The immense heat from that initial fireball heated the surrounding containers to above 240°C, which initiated a runaway decomposition reaction of ammonium nitrate, NH4NO3(s), which was stored nearby. The reaction is shown below.

NH4NO3(s) → N2(g) + 2H2O(g) + 1/2O2(g)  (ΔH uncertain)

The enthalpy change for the reaction above wasn’t easy to find, but this book by Sam Mannan claims it to be 0.175 million kilocalories per tonne, or 732,000 kilojoules per tonne. Analysis of the video recordings have estimated this second explosion to be around 21 tons of TNT equivalent, which equates to 88 million kilojoules of energy. Using calorimetry formula m = E/heat of combustion, we can estimate the mass of ammonium nitrate in this second explosion to be 8300 tonnes, which seems extremely high: four times as big as the Texas City Disaster of 1947. Either the second Tianjin explosion was the biggest ammonium nitrate disaster in history, or I’ve made an error in this part of the analysis. Let’s wait for more information and see.

The above reaction has caused hundreds of fatalities worldwide in the last 100 years. Smaller incidents occur every 2 or 3 years worldwide, around half of which are fatal. Gases are produced under extreme temperature and pressure, which expand outwards and destroy almost everything in their path. Ammonium nitrate is supposed to be handled and stored under very strict government regulations. These rules aren’t always followed (or understood) in rapidly-developing countries such as China.

The Aftermath

The products of these two explosions are calcium hydroxide, carbon dioxide, water vapour, nitrogen and oxygen, which pose zero risk to nearby residents. However, the main concern now is that other (non-flammable) hazardous chemicals such as sodium cyanide, NaCN(s), might have been tossed into the air following the first two explosions. Residents living within 3 kilometres of the blast site have been evacuated as a precaution.

Fortunately, satellite imagery shows that almost all of the smoke plume was blown eastwards over the ocean, and not back westwards and back onto the city. We’ll get a clearer picture when China’s chemical experts report their findings in the next few days or weeks.

Australia’s Future is in STEM

A recent report by PriceWaterhouseCooper predicted that 44% (5.1 million) of the jobs that exist in Australia today are at risk of ‘digital disruption’ by 2035. PwC predicts that computerisation and technology will not only create new jobs in the next 20 years but will ultimately supersede much of the existing workforce as well.

In order to realise our full potential, Australia needs an appropriately skilled workforce; a workforce fit for the future. PwC has concluded that expanding our STEM industries (Science, Technology, Engineering and Mathematics) would maximise economic outcomes for Australia in the next few decades.

The Australian economy has benefited greatly from economic reforms and from increasing demand for natural resources, mostly from China, which drove most of Australia’s growth in the early 2000s. At the same time, the PwC report says, economic growth from productivity has halved and Australia needs to develop a strong STEM foundation to guarantee economic growth after the current commodity boom has finished.

Download the full PDF report from PwC here.

Jobs most at risk from computerisation by 2035

STEM jobs being automated PwC 2015
Accountants and cashiers are most likely to become automated

Jobs least at risk of automation by 2035

STEM jobs not being automated PwC 2015
Health, education, advertising and IT are least likely to become automated

While it’s important to choose a future-proof career in one of the fields above, the benefits of doing so extend far beyond the individual level. PwC has predicted that Australia could gain a $57 billion economic boost between 2015 and 2035 if it switched just 1% of its workforce into STEM occupations. Australia’s prosperity in the next few decades appears to be highly dependent on our nation’s commitment to STEM.

Conclusion: schools and STEM businesses need to do more outreach

“Business also has the opportunity to better connect with students. This can be done by profiling emerging STEM careers, talking about workforce needs, offering workforce and internship experiences and breaking down the stereotypes and barriers that still remain today. It’s not new, but scope exists for a much more coordinated approach to engaging with the potential STEM workforce.”

Download the full PDF report from PwC here.

The Most Astounding Fact

I love this speech. Neil deGrasse Tyson was interviewed by a TIME journalist for their 10 questions page, and was asked by one reader: “What is the most astounding fact that you can share with us about the universe?” Neil deGrasse Tyson’s response was as lucid and as awe-inspiring as always. He answered the question in a relatively modest three minutes, starting with:

“The most astounding fact… is the knowledge that the atoms that comprise life on Earth—the atoms that make up the human body—are traceable to the crucibles that cooked light elements into heavy elements in their core…”

Tyson is a world-famous astrophysicist and currently serves as director of the Hayden Planetarium in New York. He’s very popular on social media and recently hosted the hit TV series Cosmos, which had the biggest launch day in TV history (and featured a 30-second introduction speech by Barack Obama).

I love Neil deGrasse Tyson’s videos because they inspire people to pursue Science. I show one or two Tyson videos to as many of my students as I can, usually at the beginning of the year. Happy New Year.

Here are some of my other favourite Tyson videos on YouTube:

How to use a Textbook: 6 Rules to Follow

VCE Chemistry annotated textbook Heinemann
My own Year 12 Chemistry textbook. Does yours look like this?

Anyone who’s spent time in a classroom knows that in any academic subject, the student who reads the textbook several times from cover to cover and makes colourful, organised notes all over it is going to excel in examinations. For this reason, I’ve been trying to get students reading their textbooks (and making great notes on them) almost as long as I’ve been teaching (since 2006). Glancing your eyes over the words in a textbook isn’t enough. How should you use a textbook properly, in any subject? There are six rules you need to follow.

1. Make notes all over your textbook

The signs of a well-used textbook are obvious: it should be inked heavily with a student’s own notes, the cover should be wrinkled and torn, and there should be at least three different brands of sticky tape holding the book together. It should flex open at 180 degrees with ease, exposing the sturdy threads of spine that prevent it from falling apart. Textbooks are designed to be used! A pristine textbook is the hallmark of a student who doesn’t study. Treat your textbook as your own, and prove that you’ve read it by plastering it with your own notes. Taking notes while you read has been proven to increase comprehension levels by up to 50%… and it makes revising much easier, too. (Just re-read your notes!) What do great textbook notes look like? In all the important sections (and that’s most sections), you should draw a horizontal line in the margin to separate each paragraph. Each paragraph should be summarised in eight words or fewer in the resulting spaces. (See next week’s post on How to Make Great Notes.)

2. Translate key words in your textbook

If you’re studying in a second language, or if you speak more than one language, it will help you to translate key terms into your first language in your textbook. Circle important new words and phrases in the textbook and write the words in your first language beside them.

3. Build vocabulary lists & concept lists based on what you read in the textbook

Vocabulary lists need to contain three things: the word in English, the definition in English and the word in your first language (if not English). Vocabulary lists relevant to the topic you’re studying need to be placed large in prominent places: your bedroom wall (if you’re a student) or on the classroom wall (if you’re a teacher). Build word lists and learn these vocabulary lists using spaced repetition software such as Pleco for iOS or ProVoc for Mac. These apps will quiz you on the vocabulary you’ve been reading at exactly the best time-intervals to ensure you beat the famous “Ebbinghaus forgetting curve”!

4. Highlight your textbook carefully

Highlight important concepts, but don’t go overboard. If you highlight everything, nothing stands out! Use your highlighter and your pen in approximately a 1:1 ratio: they should occupy approximately the same surface area on each page. The best use of a highlighter is to highlight not only key sentences in the book, but also to highlight important notes and summaries that you’ve made yourself. Key things to highlight in a Chemistry textbook, for example:

  • Formulae that need to be learned (lead-acid battery half-equations)
  • Ions (their names, formulae, charges and colours)
  • Acronyms and mnemonics that you’ve created from bullet lists
  • Phrases that examiners really care about (“carbon-carbon double bonds” and “alternative reaction pathway”, for example)

5. Make your own notes on paper using the textbook and external sources

Learning is consolidated further in your mind when you translate the notes you made in the textbook margins to make your own hand-written notes on paper. Make a first set of notes on A4 paper. Use a logical colour scheme and concise language and diagrams to consolidate the key information. Use the textbook as the basis for at least 90% for your notes, but also add information (no more than 10%) from other textbooks, news articles and examiners’ reports. Keep your notes safe, organised and visible. Hand-write your notes! Research has shown that people consolidate much more of the information they’ve read into their long-term memory when they hand-write their notes than when they use a computer to type them up. There are several theories that attempt to explain why: the most convincing of these are that computers can be distracting, that typing requires less hand-to-eye coordination than writing, and that typing is slower than writing (if we include colours, diagrams and large amounts of superscript, subscript and the special symbols required for Chemistry). Always hand-write your notes.

6. Always know the textbook references for your current topic of study

Not all teachers give textbook references for the topics they’re teaching in class. But knowing the textbook reference is crucial if students want to review what they’ve learned after the lesson. How can you make your own notes or do further reading if you don’t have a textbook reference? Even worse, many teachers provide students with their own notes, summaries or PowerPoint slides that accompany a lesson. I’m strongly against this. Learning happens in the act of taking great notes, and a teacher who gives their students pre-made notes is depriving their students of the opportunity to learn.

Learning happens in the act of taking notes, and a teacher who gives their students pre-made notes is depriving their students of the opportunity to learn.

If your teacher gives you notes or PowerPoint slides, don’t use them. Kindly ask your teacher for a textbook reference and make your own notes directly from the textbook instead. The textbook will always be more coherent, more comprehensive and more correct than any notes that your teacher distributes in class. For more information, watch this 10-minute clip from ThePenguinProf: https://www.youtube.com/watch?v=xOlJiMKEjpY

The 8 Benefits of Home Tutoring (VCE Chemistry)

VCE Chemistry home tutoring MelbourneIf you’re looking to boost your Study Score in VCE Chemistry, you should consider hiring a home tutor. Home tutoring provides quality contact time that often isn’t available in school. Home tutoring has eight main benefits:

1. Students get a thorough review of what they’ve learned in class with a home tutor

Studies show that a student who leaves a class without having made any notes is able to recall about 10% of what was taught as they leave the classroom. Spaced repetition reviews with a home tutor can increase memory recall of knowledge being taught to well over 80%. By remembering more of the course content, students are primed with a foundation to understand and apply that knowledge much more easily.

Tutors can also explain concepts much faster and more succinctly than teachers in the classroom because they’re working in a one-to-one environment. Without distractions, and without having to divide their attention between 20 or more students, a home tutor can explain clearly in ten minutes what might take a whole lesson if taught by a teacher in a classroom.

2. Students are more motivated to do their homework with the guidance of a home tutor

Students who work on homework tasks with a home tutor tend to stay focussed for longer periods of time than those who don’t. With a home tutor, students can ask questions while doing their homework and spend less time getting ‘stuck’ because they get instant support when they need it. Home tutors can also question students and ask them to explain the answers they’ve given to check and consolidate understanding.

A tutor can also break down even the most complex homework questions into a series of simpler questions that the student is able to complete. With home tutoring, students complete their homework assignments on-time and always to a very high standard.

3. Students can pre-learn what’s about to be learned in class before a topic begins

Imagine walking into a classroom already knowing the gist of what you’re about to learn. If a student learns a new topic with a home tutor, the classroom environment becomes the place for revision rather than first-time learning. Learning a complicated subject like VCE Chemistry is far more efficient this way. Probably the greatest benefit of pre-learning with a home tutor is that students can then make a great impression among their teachers and peers by grasping ‘new’ concepts extremely quickly in class, which gives them a huge confidence boost in the subject!

4. Students receive adequate homework tasks

Not all schools set enough homework tasks. You can ask your tutor for more homework questions. Unlike most classroom teachers, a home tutor knows your student’s exact strengths and weaknesses in the subject with great detail, and can select homework questions from a wider range of sources to help your student improve on the exact topic areas where they need more practice.

5. Students receive very, very detailed feedback on their written answers with a home tutor

In a VCE Chemistry examination, writing “the solution decolourises from blue to colourless” might earn one mark, whereas “the solution loses some of its colour” will not. Labelling ethanol in a combustion equation as “liquid (l)” might earn one mark, whereas “aqueous (aq)” will not. A classroom teacher marking dozens of tests can easily miss the subtle nuances of language that VCAA examiners are be looking for, or might not have the time to explain exactly why a question was answered incorrectly to each student in a class.

Home tutors can examine, question and correct every answer the student givesno matter whether it’s written or spoken—and provide instant feedback on the student’s responses as they work. Instant feedback is very motivating and time-saving for students.

6. Students get a second voice explaining new concepts

If the class is quite large, or if the teacher has a heavy accent, not all students will understand all of what the teacher is saying. Home tutors can explain the course concepts one-to-one in a quiet, home environment, which is efficient, engaging, and is always done in a way that the student understands.

7. Students get an extra set of textbooks

Home tutors always coach students from different schools. Hiring a home tutor allows you to gain access to a second set of textbooks, past paper examinations and practice materials from that teacher, which your current school might not have access to.

8. Students get meta-study tools from home tutors as well

Home tutors do more than just review content, help with homework assignments and pre-teach upcoming topics. They also provide students with:

  • personalised examination revision timetables
  • examination tips
  • thorough notebook checks
  • general study tips
  • note-taking strategies (e.g. Cornell)
  • reading strategies (e.g. The Reading Process)
  • and more… 

The benefits of home tutoring allow the student to maximise their potential in homework, tests and examinations not only at VCE level, but throughout all the years of university as well. For as long as a student is sitting some kind of examinations, the student will be using above the strategies that a home tutor can provide.

As a VCE Chemistry and Physics teacher, I can testify that students with regular home tutoring are generally happier and more focussed in class, pursue their homework tasks more thoroughly and gain higher scores in tests because they’ve had the one-to-one time required to learn all the subtle nuances in language that examiners are looking for.

Find a tutor fast in Melbourne’s south-east suburbs.

Leave me a message using the contact form below.

Australia sees its last lunar eclipse until 2018

The full moon above Australia will be “blood red” according to some reports as the moon enters the fringes of our Earth’s shadow called the penumbra tomorrow night.

The Moon’s redness will be a result of the selective scattering of blue light by our atmosphere, which causes only the longest wavelengths (red) light to reach the edges of the Earth’s shadow (called the penumbra). Our huge, red Moon will pass through the penumbra as it orbits the Earth then become momentarily invisible as it traverses the centre of the Earth’s shadow (called the umbra).

SMH lunar eclipse science infographic jameskennedymonash
Image from Sydney Morning Herald

Melbourne is the perfect viewing spot for this spectacular eclipse. The reddened Moon will also appear extremely large (this is an optical illusion that results from the Moon being very low in the sky!).

Date: Wednesday 8th October, 2014
Time: Moonrise is at 7:21pm. Eclipse starts at 7:30pm and finishes at 11:30pm.
Location: low in the eastern (or north-eastern) sky

Penumbral Eclipse begins: 7:17 PM
Partial Eclipse begins: 8:18 PM
Full Eclipse begins: 9:27 PM
Maximum Eclipse: 9:55 PM
Full Eclipse ends: 10:22 PM
Partial Eclipse ends: 11:32 PM
Penumbral Eclipse ends: 12:32 AM

For more information: http://www.timeanddate.com/eclipse/in/australia/melbourne

The next time this happens will be in 2018. Make sure you get outside to see this one tomorrow night!

Book: Entanglement: The Greatest Mystery in Physics

Entanglement: The Greatest Mystery in Physics
Picture from Amazon

Some light reading for a quantum physics post-doc. Inaccessible for most.
284 pages, ★★★

The topic is fascinating. Entangled photons (light ‘particles’) are known to exhibit what Einstein famously called “spooky action-at-a-distance”. Entangled photons exist in every possible state (and even in every possible position) until one of them is observed. The observation of one of the photons, no matter how far away it has travelled, instantly (literally instantly—at infinite speed—not just at the speed of light) influences the other photon by deciding its ‘state’. This has puzzled physicists for decades and has started to fascinate the public in recent years.

However, this book is inaccessible for me. I haven’t studied physics to this high a level. Its diagrams are incomprehensible for me because I’m not familiar with the symbols—and the book, foolishly, doesn’t define them. There are no analogies to help me understand these weird phenomena, and the characters (e.g. Einstein) don’t come to life to the extent that they do in Michio Kaku’s books. Entanglement makes light holidaying read for an established quantum physicist but is inaccessible and irrelevant to most other people. Fails to engage the public. ★★★

Book: Einstein’s Cosmos

Einstein's Cosmos by Michio Kaku

Excellent modern physics primer that’s mostly a biography of Einstein
203 pages, ★★★★

Author Michio Kaku is a very talented science writer. He is one of the few science writers who achieves the near-impossible goal of communicating advanced science accurately, in a way that’s easy to understand, and with added humour throughout. Most writers can’t do that!

In Einstein’s Cosmos, Kaku explores how Einstein’s life story shaped almost all of modern physics. The question of uniting two seemingly incompatible theories is a recurring theme in this book (and in physics itself). The first instance is on page 11, where we learn how Einstein was faced with the problem of reconciling Newton’s forces and Maxwell’s fields. “One of them had to fall”, Kaku writes. Einstein would topple Newtonian forces and replace them with something beautifully simple.

Kaku’s analogies are very easy to understand. To illustrate length contractions and time dilations using cars, he slows the speed of light down to 20mph and describes what each observer would see.

We’re now faced with an incompatibility between general relativity and quantum field theory. Both hold true at different scales, but they don’t seem to overlap properly as part of a grand “unifying theory”. Just as Einstein unified Newton’s and Maxwell’s equations, physicists are now faced with the task of unifying general relativity and quantum field theory—and the book almost exactly as it started.

Beautiful! ★★★★

 

23andMe effectively shuts down (Dec 7th, 2013)

23andMe Logo

Try typing “23andMe scam” into Google. You’ll be directed to my most popular blog post of 2013, in which I posted the results of my genetic test with 23andMe. It’s the third most popular search term leading into this website (behind Buddhism and Hunger Games in 1st and 2nd place). 🙂

You can read the original post here.

In December 2012, I spat into a tube and sent it to 23andMe, a genetic testing company in California. In January 2013, they sent me the results of my genetic information over several days. I sifted through swathes of data and posted all the conclusions worth hearing onto my blog. There were 12 of them.

As someone trained in biology, particularly in genetics, I knew how to interpret the genetic data. I knew to ignore all of the health information, especially the vague correlations in tiny studies with genes of unknown function, and posted only the inconsequential genes and the ancestral information instead. This wasn’t a privacy concern—I posted all the findings that I found genuinely interesting. But I did omit any findings that I knew to be total bunk.

In one blatant statistical blunder, 23andMe told me I had a 1.5x greater chance than the “average person” of getting cleft lip. In another, they told me I had double the likelihood of getting certain diseases for which environmental factors were by far the greatest predictors. 23andMe doesn’t consider environmental factors and doesn’t differentiate between meaningful and meaningless statistics.

People not trained in genetics or statistics wouldn’t have the same level of insight that I did. Some customers could read all the misleading data like numbers on a die, and then make false conclusions as a result. 23andMe never did enough to protect its customers from such confusion. In fact, they passively encouraged it with gimmicks like “Genetic Melody” and the inclusion of vague correlation studies in tiny populations for very serious diseases. This data could worry people unnecessarily. While 23andMe communicated science much better than did the average newspaper, there was still a gaping linguistic chasm between scientists and consumers. The way that 23andMe reported health information to the public was still in need of major improvement.

But that improvement didn’t come quickly enough, and last week, the FDA shut down 23andMe’s entire genetic health reporting service. Its ancestry service lives on, which has always been 23andMe’s most interesting component in my opinion, and only new customers (after November 22, 2013) will be affected. Nevertheless, this decision is a huge blow for 23andMe and a momentous victory for advocates of science communication.

Rightly so. The fact that so many people are typing (and I see you!) 23andMe scam into Google indicates that a problem is at foot.

So while I’m pleased it’s been shut down, I also regret not making these shortcomings clearer in my 23andMe post one year ago. Despite the comments and emails I received from people trying to make sense of their 23andMe results, I forgot that not everyone is science-literate.

Fortunately, the FDA remembered. Thank you.

Book: Nelson Chemistry VCE Units 1 & 2

Nelson Chemistry VCE Units 1 & 2

Colourful VCE Chemistry textbook especially good for visual learners
492 pages, ★★★★★

I care a great deal about colour and design. My revision notes always have a colour-scheme that makes sense to me, and I draw colour-coded character maps of the novels that I read (see examples in the “Popular Today” section on the right!). Information makes so much more sense to me in visual form. You can see some of those visualisations on the infographics section of by blog.

That’s one of the reasons I loved this VCE Chemistry textbook. While it doesn’t say so explicitly, it’s noticeably designed for visual learners such as myself.

First, I love the varied yet consistent use of fonts. The main text is set in Garamond on a white background, which makes it easy on the eyes when reading. Titles, tables and questions are set in a tall, rare, old-fashioned sans-serif font on a colourful background, which gives this book its unmistakably unique appearance. Annotations and extra information is set in a neutral sans-serif font (similar to Helvetica) off to the side, usually in colour, and balances the old-fashioned feel of the other two fonts beautifully. The whole book is visually pleasing, which makes me want to spend longer looking at the pages!

I also love the visual summaries at the end of each chapter. (This is where Heinemann—another VCE Chemistry textbook—falls down.) In particular, the visual summary on page 156 explains the properties of metallic bonding clearly and beautifully in one diagram. The diagram made a relatively complicated topic very simple to understand.

Nelson VCE Chemistry 1 & 2 page 156

I hope textbooks become more and more visual. Maybe with the introduction of the iPad in schools, colourful diagrams and interactive animations will become more common in the classroom. I hope so.

I’m also not alone here. Many students I’ve taught in schools are actually averse to reading the main text in a textbook. They don’t even notice the Garamond—they only see the titles and diagrams. While we still need to focus heavily on improving literacy on the one hand, we also need to acknowledge this trend towards more visual ways of presenting information on the other.

As a teacher, I advocate more ‘translation’ activities as discussed on PEELweb.org and as is routinely done with ESL students in IELTS: set students the tasks of translating diagrams into prose and vice-versa. We need to incorporate visual learners in our curricula, for which, this textbook is an excellent starting point. ★★★★★

Book: Heinemann Chemistry 2 Enhanced (VCE Units 3 & 4)

Heinemann Chemistry 2 Enhanced cover


The best textbook for VCE Chemistry Units 3 & 4
496 pages, ★★★★★

Heinemann Chemistry 2 Enhanced (Heinemann 2) is the best VCE Chemistry textbook in existence. There are two other major brands (Nelson and Jacaranda) but Heinemann 2 beats both of them in terms of comprehensiveness and clarity.

I read the whole book from start to finish in preparation for teaching VCE Chemistry. I love the clarity, the use of full colour and the connections to real life in this book. I also love how the most difficult unit,  Unit 4, consists of hard and easy chapters in alternation! Left-brained chemical production processes are interspaced with right-brained “chemistry in society” chapters, which are easier to understand. The whole book is organised according to the VCE Chemistry Study Design, too—and the Key Knowledge from the Study Design are pasted at the start of each chapter.

Heinemann 2 isn’t perfect, though. I noticed two errors:

Page 91: the infra-red (IR) spectrum of ethanol is wrong. Compare the book’s example (top) with a typical example found online (bottom):

Ethanol WRONG Infrared Spectrum

Ethanol Infrared Spectrum

Why is the O-H stretch in Heinemann 2‘s spectrum so narrow and short?

Page 445: the bottom paragraph on tin plating is very unclear. The book uses “tin” to refer both to the “tin can” and to the “tin plating”, even though only the latter is actually made of tin. An extract from Heinemann 2 is below.

Confusing Extract from Heinemann 2

…that’s confusing!

With the exceptions of IR spectroscopy and tin plating, Heinemann 2 gives you comprehensive coverage of all the topics in VCE Chemistry. As long as you look up those two topics on ChemGuide, Heinemann 2 is the only textbook you’ll need to buy. ★★★★★

More resources might pique students’ interest, though. Try these websites:

  1. ChemGuide — succinct, text, covers VCE well ★★★★★
  2. Richard Thornley — tutorials for VCE and a little beyond ★★★★★
  3. Kahn Academy — tutorials for VCE and far beyond ★★★★★
  4. ShowMe — covers most of VCE ★★★★

And try these iPhone apps for organic chemistry:

  1. Organic Chemistry Nomenclature — revision flashcards ★★★
  2. MolPrime — great for drawing organic molecules with your finger ★★★
  3. ChemSpider — look up properties of the molecules you drew in MolPrime! These two apps work seamlessly together. ★★★

12 things I learned from my 23andMe results

Just before Christmas, I spat into a plastic tube and sent it to 23andMe: a genetic testing company in California.

23andMe Logo

 

23andMe tests one million SNPs (minor changes) in a person’s genome, many of which are linked with known, inherited traits. Their results reveal a wealth of information about your health and ancestry, ranging from eye colour and bitter taste perception to the presence of major genetic diseases and your extended family tree. Meaningful results are then sent to you by email within a few weeks.

All this is priced well-below cost, at just $99 plus shipping. It was totally worth it. Here’s a list of the 12 most interesting things that 23andMe revealed about me.

1. No carrier status

Fortunately, I carry none of the 48 diseases for which 23andMe tests. That’s good news! None of these diseases will affect me, nor will they be passed on to my children.

2. HIV-resistance: CCR5 +/Δ32

This is awesome—I carry one copy of the HIV-resistance allele! A very small percentage of people are lucky enough to have this allele. The virus which heterosexual, monogamous vegans almost never encounter just got even harder to get.

3. Can’t taste bitter: TAS2R38 -/-

The TAS2R38 gene encodes the receptor that detects PROP and related bitter plant compounds. I have a relatively common mutation that is insensitive to PROP. My version of this gene improves the taste of bitter foods—including poisonous ones.

4. Can digest lactose: MCM6 +/+ (regulates LCT)

I don’t like milk, but at least I can digest it. I have two fully-funcional copies of the lactase enzyme, and both will remain active throughout adulthood.

5. Slow caffeine metabolism: CYP1A2.

Caffeine is primarily metabolized by the liver enzyme cytochrome P450 1A2. My version of this enzyme metabolises caffeine slowly (just like 99% of people). I learned that I’m not one of the 1% of people who are virtually insensitive to caffeine.

6. Ancestry

British and Irish: 67.6%; French and German: 5.8% (4 gen); Scandinavian: 0.1% (10 gen); Northern European: 24.0% (2 gen); Southern European: 1.2% (6 gen); Other European: 1.1% (7 gen); Middle Eastern/North African: 0.1% (10 gen); unknown: 0.1%.

James Kennedy ancestry results
Click to enlarge.

I calculated generations by taking the percentages, log base 2 and multiplying by -1.

Most of my ancestors were from “Britain/Ireland”, or “North Europe”, which includes Britain and Ireland. But interestingly, there was a little more diversity than I expected. one of my (great-?)great-grandparents was either French or German (see number 11). Six generations ago, there was someone from South Europe in the family. Ten generations ago, there was one person from Scandinavia, and one person from the Middle East or North Africa.

7. My blood group: A Rh(-) Di(a-b+) K-k+ Kp(a-b+) Jk(a+b+)

I already knew my blood group, but it was interesting to learn that blood groups are a complicated business. For everyday purposes, though, I’m an A-negative.

8. 3.1% Neanderthal DNA (very high)

Neanderthals looked like caricatures of Celts: white, brutish, red-haired and freckled. The average Caucasian has 2.5% neanderthal DNA, and I have 3.1%, putting me in the 98th percentile. It means that I’m “whiter” than most white people.

9. Maternal haplotype: H3 (Western Europe)

H3 is a minority European haplotype found in Western Europe. (Most natives are H1 haplotype.) Over the last 10,000 years, H3 declined in Europe due to random genetic drift, but remains prevalent today in the Basque region (probably because they mixed less frequently with outsiders). There’s almost no phenotypic difference between H1 and H3, so until further research is done, this is merely an interesting fact.

Maternal haplotype H3 map
Maternal haplotype H3 map
10. Paternal haplotype: R1b1b2a1a2f2 (Ireland)

Obviously. My paternal family is Irish and my paternal haplotype proves it. R1b1b2a1a2f2 is distinctively Irish.

11. One arm of Ch1 is entirely French/German

This is very interesting. I’m British, so while having a little French/German DNA is normal, having it all on one arm of one chromosome indicates that it probably all came from one, recent ancestor (no more than 4 generations ago). Given that French/German DNA is unique in going mostly undetected using 23andMe’s testing methods, and that the possibility of inheriting an entire chromosomal arm halves with each generation, this French/German ancestor was probably a great-grandparent. I didn’t know this.

James Kennedy French/German DNA
My French/German DNA (dark blue) is mostly on one chromosome.
12. Eight chromosomes contain one arm with no British/Irish DNA at all.

Chromosomes 1, 8, 9, 10, 11, 18, 20, and 22 contain one arm with no British/Irish DNA at all, and one arm with almost 100% British/Irish DNA. Given that one arm is inherited from each parent, this indicates that either I (or each of my parents) had one parent who was purely British/Irish, and one who was a more mixed “Northern European”.

James Kennedy's British/Irish DNA from 23andMe
Eight chromosomes have one arm with no British/Irish DNA (dark blue) at all. This indicates one recent family member of mixed, Northern European origin, not just from Britain and Ireland.

Additionally, 23andMe found 833 distant cousins who have also had their DNA tested. I share great-great-grandparents with the closest of these cousins, but none of them have surnames that I recognise. Some of them live in Wales, but that’s probably just a coincidence. The process of trying to link the family trees, if I do it, would be a long one.

I wanted to do this years ago, but it used to be too expensive: $999 plus a monthly subscription (whatever for?) The price then dropped to $499, $299 then $249 (last year), before finally hitting $99 before Christmas 2012—without any monthly fees. That final price drop prompted me (and nearly a million others) to buy the test.

I highly recommend 23andMe. The data arrives little by little, so there’s something to look into (and reference papers to read) each day. Anyone interested in their own health or ancestry should give it a go.