Monthly Archives: August 2015

Chemistry Task Words

Chemistry VCE task words verbs for Chemistry education and instruction
Click for a PDF version of these task words

RTQ! This is one of the most common sources of errors in Chemistry examinations. When I sat 2014’s VCE Chemistry examination, I lost 5 marks in the paper for not reading the question! Your teachers will have told you to ‘read the question’ or ‘RTQ’ as well.

Task word errors can be avoided in two ways. First, learn the exact meanings of each task word. This is particularly important for EAL Chemistry students. Second, highlight the task words in a question (just as you would highlight the important information in a complicated titration question).

For example: “Explain how the different intermolecular forces in butane and butan-1-ol give these two compounds different boiling points. 3 marks

In your answer, you will need to explain the effect of intermolecular forces. This means you’ll need to write why the butan-1-ol forms hydrogen bonds (due to the polar nature of the hydroxyl group) whereas butane forms only dispersion forces with its surrounding molecules (due to the non-polar nature of the molecule). You’ll also need to make some kind of comparison (which is hinted at by the word, ‘different’) in order to get all 3 marks.

Example 3-mark answer: “Butan-1-ol forms intermolecular hydrogen bonds with the surrounding molecules due to the polar nature of the hydroxyl group (O-H bond). Butane forms only dispersion forces with its surrounding molecules due to the non-polar nature of the molecule. Hydrogen bonds are stronger than dispersion forces and thus require more energy to break. This results in a higher boiling point for butan-1-ol than for butane”.

One mark would be awarded for each of:

  • Explaining the intermolecular bonding of butan-1-ol
  • Explaining the intermolecular bonding of butane
  • Comparing the relative strengths of the two and relating this to boiling points

In a 2-mark answer, the student might omit the comparison step:

Example 2-mark answer: “Butan-1-ol forms intermolecular hydrogen bonds with the surrounding molecules due to the polar nature of the hydroxyl group (O-H bond). Butane forms only dispersion forces with its surrounding molecules due to the non-polar nature of the molecule.”

In a 1-mark answer, the student might only mention one of the two molecules, or might only make a comparison without explaining why these two compounds display different types of intermolecular forces.

Example 1-mark answer: “Hydrogen bonds formed by butan-1-ol are stronger than dispersion forces formed by butane and thus require more energy to break. This results in a higher boiling point for butan-1-ol than for butane”.

In that latter example, the student didn’t explain the reasons for the differences in intermolecular bonding – they merely stated them.

Task word Chinese Description
Calculate 计算 Write the value of a number (include equations)
Compare 比较 Write the similarities and differences between
Evaluate 评价 Write arguments for and against
Define 确定 Write the exact meaning of
Describe 描述 Write details about (a thing or a process)
Discuss 讨论 Write reasons for and against
Distinguish 区分 Write the differences between two or more things
Explain 讲解 Write details to give the reader an understanding of
Find/State Write (sometimes by doing calculations)
Identify 鉴定 Write which one
Illustrate 说明 Write something and draw a labelled diagram as well
Indicate 表明 Write which one (usually on a given diagram)
List 列出 Write a list
Outline 轮廓 Write a summary
Suggest 建议 Write a reason for a phenomenon
To what extent 到什么程度 Write whether a reaction is complete (→) or incomplete (↔).

Watch task words in the examination… and make sure you answer the question!

3 Things You Take With You from Year 12

1) Friendships

Memories and connections are some of the most valuable things you’ll take with you from Year 12. Keep in touch with as many people as possible both officially (using alumni networks) and unofficially (using social media). People move in different directions after graduation and you’ll be surprised at how your friendships evolve, too: classmates who were mere acquaintances during school might become very close friends in five years’ time. Keep in touch with all your classmates to make sure you don’t miss out on these future business connections, too. You might even meet again one day sitting opposite each other at a job interview!

2) ATAR

Remember that your ATAR is only a means to a much more meaningful goal: it’s the key to a university course of your choice. Strive for an ATAR that’s high enough: there’s no need to stess yourself out by aiming for a ‘perfect’ score of 99.95. Your ATAR is like a disposable key: it gets you into university but doesn’t help you while you’re there. Nobody asked me what my A-level results were throughout my undergraduate years at Cambridge. High-school results simply weren’t important.

3) A Relentless Work Ethic

You’ve worked harder in Year 12 than you’ve ever worked in your life. If you want to be successful, you’ll have to maintain this level of hard work – or even increase it – to accomplish your goals in life. You’ve learned the difficult way that in Year 12, going to school and doing all the required homework isn’t enough. You’ve figured out in Year 12 that you have to spend hours reading the textbook by yourself, doing practice question sets that aren’t on the course, and making summary notes that your teacher will probably never see in order to get a high grade.

The relentless work ethic you’ve garnered will help you to conquer bigger obstacles in the years that follow. Give every major event in your life at least as much passion, dedication and preparation that you gave to your VCE examinations and you’ll be sufficiently prepared for the challenges that await you in the future. VCE is pre-season training for life.

Is there anything I’ve missed from this list? Is an ATAR more than just a “key to a university course”? Let us know in the comments section below.

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.

What’s in a name?

what's the most intelligent baby name in australia

I’m excited to say that my wife and I are expecting our first baby in November: we’re expecting her to be born shortly after the VCE Chemistry examination! Like most new parents, I’ve been pondering baby names in the last few weeks. In particular, I’ve been looking for a girl’s name that’s traditional, popular and sounds intelligent.

The first two criteria are easy to satisfy: we can look to the Royal Family for traditional names; and the most popular baby names of 2015 are just one Google search away. However, the third criterion is a bit more difficult: what’s the most intelligent girls’ name? With this question in mind, I set out to find the most intelligent first name in Victoria based on empirical evidence from three publicly available databases.

Method: combine three public databases

I downloaded the list of 40+ VCE study scores for 2014 from the Herald Sun’s website. I cleaned the database using Microsoft Excel and obtained a neat, searchable list of 13,478 students and their VCE results that looked like this:

what's the most intelligent name in Australia
Total number of records in my database: 13,478

I removed outliers by deleting all the rare names from the list. Only names with 5 or more high achievers (40+) were included in the final analyses. Admittedly, this removed most Chinese students from the database because they have very unique first names, but I’ll expand on the implications of this later.

I then merged this database with the list of surnames and their prevalences that I obtained from IP Australia, and a similar list of first names from the NSW Government website. Now, I could query my database with interesting questions such as, “Which first name got the highest average ATAR in 2014?” and “Which surnames had the highest proportion of 40+ study scores?” The results were fascinating, and will be of some help when deciding a name for a newborn baby.

Results

Table 1: Students called “Victor” achieved the highest mean ATAR in 2014

The 50 first names in Victoria with the highest ATAR (2014)
Victor is the most academically successful name in Victoria for 2014

The ATARs of students called Victor were far higher than the ATARs of students with any other first name. (Is that because we live in Victoria?) I’ve coloured the names blue, pink or green to represent whether the names are male, female or both.

Table 2: Hilary, Judy and Derek had the highest proportion of 40+ study scores in 2014

I added some more columns to the spreadsheet to estimate what percentage of students born with those 50 first names in 1997 in Victoria achieved a 40+ study score in at least one subject. According to my estimates, every student called Hilary, Judy or Derek achieved at least one study score of 40 or above in their 2014 VCE examinations. Correct me if I’m wrong.

forty plus first names
Students with these names excelled in at least one subject. Percentages are estimates based on 1997 population information.

Where are all the Asian names? I mentioned earlier that I removed all the rare names to eliminate outliers from the database. (This is standard practice.) The vast Chinese character set gives rise to literally millions of possible first names, which means that many Chinese students have unique first names and most of them were therefore excluded from my previous analysis. For a truer reflection of the influence of Chinese-background students in VCE, we need to look at students’ surnames instead.

“…every student called Hilary, Judy or Derek achieved at least one study score of 40 or above in their 2014 VCE examinations.”

Table 3: Students with the surname “D’Souza” achieved the highest mean ATAR in 2014

I re-ordered the list of 13,478 students to show the mean ATAR for each surname. Surprisingly, the highest achieving surname was D’Souza, which was originally Portuguese but is now found worldwide. According to Wikipedia, “A prominent family carrying the spelling de Sousa emigrated from Portugal to Goa during mid 1956 before leaving to Hong Kong. This was followed by a third relocation in the mid 1960s, where they now reside in Melbourne, Australia. The family donated their property in Hong Kong to Franciscan nuns.” Their success in Melbourne continues to this day.

top 50 surnames in vce 2014
Academically well-rounded students get a high ATAR

Chinese surnames dominated the rest of the top 50. The second-place surname, Chin, for example, comes from Qin Shi Huang, the first ever Emperor of China. He was born in 269 BC and is still regarded as one of the boldest emperors in Chinese history. It’s also believed that the English name for ‘China’ was derived from Emperor Qin Shi Huang’s name.

A few English, Korean, Irish and Vietnamese surnames also made it into the top 50. Kennedy was 273rd out of 379 surnames.

Table 4: Chinese surnames dominate 40+ study scores

An ATAR is an aggregate score of 4 to 6 subjects including English and (usually) Maths, and thus provides an indication of how well-rounded a student is academically. Next, instead of finding lists of well-rounded students, I wanted to find out which students excelled in just one or more subject. I chose study scores of 40 or above as a benchmark. I then divided the number of students with each surname who achieved at least one study score of 40+ by the number of people in Victoria who had that surname. The result is a fairer indication of which students excelled in one or more area, but didn’t necessarily excel in all subjects. The results were fascinating!

surnames with 40 plus atar
50 Shades of Red: these students excelled in at least one subject

Three Sri Lankan surnames and 47 Chinese surnames dominated the top 50. Interestingly, an estimated 23% and 22% of students surnamed Jayasinghe and Ranasinghe achieved a study score of 40+, respectively, which is many times higher than the VCE student population as a whole.

Conclusion: Names Matter!

Evidence has shown that boys who are given girls’ names (e.g. “Sue”) are far more likely to exhibit poor behaviour and low academic outcomes than their peers with more appropriate, boy-ish names. . A study involving 5,000 job applications revealed that applicants with “Black-sounding” names like Lakisha and Jamal were 33% less likely to land a job interview than their equally-qualified counterparts with “White-sounding” names such as Emily and Greg. In South Carolina, Patrick McLaughlin presented evidence to support the Portia Hypothesis, in which women with masculine-sounding names were more likely to succeed in the legal profession than an otherwise-identical counterpart.

Exactly how much do names matter? To what extent does a name determine your destiny? Let me know in the comments section below.