Simulating the Half Life of a Radioisotope

Syntactic and Syndiotactic are NOT Synonymous

 

Question 20 from paper 1 of the QCAA chemistry exam 2022 is shown below. Can you answer it?

 

 You can if you make a couple of assumptions first:

1/ The 3D structure isn't given, so you have to assume (given the possible answers) that methyl groups above the chain are in fact coming out of the plane, while methyl groups below the chain are behind the plane.

2/ You have to assume that "syntactic" is a misprint of "syndiotactic" since there was no mention of this being a composite material.

Then you can choose (A) as the answer, and according to the answer sheet you would be correct.

 

However, here is an excerpt from the draft new Queensland Chemistry syllabus (for implementation in 2025 I believe),

      "Describe the structure features of

           -polyethene (LDPE and HDPE), polypropene (syntactic, isotactic and atactic) and                                             polytetrafluorethene."

(Cross my heart, this is what is says, the syllabus writers seem to have difficulties with adjectives as well as chemical nomenclature, where are the round brackets around tetrafluoroethene?)

 

So, it appears that students will study tacticity of polymers but only isotactic and atactic not syndiotactic, then they will look at composite materials in the form of syntactic foams.

Really?

 

Dear Queensland Chemistry syllabus and exam writers, the 3D structure of a polymer results in an isotactic, syndiotactic or atactic polymer.

A syntactic foam refers to a composite material in which hollow spheres are bound together by a polymer.

World Logic Day 2024

 January 14^th is World Logic Day, the perfect day to test how logical a chatbot like ChatGPT is right?

This is the question I asked,

"Each side, including the lid, of a cubic steel box has a surface area of 2500 cm². Twenty coloured balls are placed in the open box. There are twice as many red balls as blue balls inside the box before the lid is welded shut. What is the probability of removing a red ball from the box?"

What is the logical answer to this question? If you are a human being, the logical answer is 0% because if it is a cube and all the sides (including the lid) have the same surface area then there is no hole on any side to withdraw a ball, so when the lid is welded shut you cannot remove a ball.

What is the answer if you are a chatbot? 

This was ChatGPT's response (no additional comments from me, the chatbot's approach is already hysterically funny)...

"Given that each side, including the lid, has a surface area of 2500 cm², and there are 6 sides in total, the total surface area (SA) is given by:
SA = 6 x side²

Since SA = 2500 cm², we can set up the equation:

2500 = 6 x side²

Solving for the side length (side):

(side)² = 2500/6

(side)² = 1250/3

(side) = √1250/3

Now that we have the side length, we can find the volume ( V ) of the cubic steel box:

V = (side)³

V = (√1250/3)³

Now, assuming there are twice as many red balls ( R ) as blue balls ( B ), we have   R = 2B .

The probability ( P ) of removing a red ball from the box is given by:

P(Red) = Number of Red Balls/Total Number of Balls

P(Red) = R/(R + B)

Substitute ( R = 2B ) into the equation:

P(Red) = 2B/(2B + B}

P(Red) = 2B/3B

P(Red) = 2/3

Therefore, the probability of removing a red ball from the box is 2/3." 

Logical? 

Maybe not, but it does share some similar characteristics with typical student responses (pre chatbots), that is, 

a) Ignore the question and just start doing some random calculations until you arrive at some kind of answer.

b) Ignore units.

c)  Never, ever, under any circumstances check your answer to see if it makes any sense.

ChatGPT score 0% (which is apparently equal to 2/3).

Proving ChatGPT is An Idiot

How intelligent is OpenAI's chatGPT?

Here is the question I asked,

"If my mother had 3 sons and each of my brothers has 2 children, how many cousins do I have? "

 

People, being intelligent and logical, would realize there is no sensible answer since there is not enough information in the question, but chatGPT, being neither intelligent nor logical, replied (with HORRIFIED INTERJECTIONS from yours truly),

"In the scenario you described, you are one of the three sons...."

EXCUSE ME! I am definitively female ... cisgender female (she/her)

"...Each of your brothers has 2 children. Therefore, each of your brothers has 2 children, and since you are one of the sons, you also have 2 children. This means that each of the three sons (including yourself) has 2 children.

So, if you sum up the children of all three sons (including yourself), you have a total of 3 sons * 2 children per son = 6 children...."

YOU SEXIST SO-AND-SO! It's 2024 and women are still invisible in society!

"...These 6 children would be your nieces and nephews...."

WAIT! HOLD ON ... 6 children in the next generation OK'ish, but 2 of them are "mine", therefore I'd have 4 nephews and nieces in total, right? (Or is this your way of acknowledging that I may not be male?).

"... Each of your nieces and nephews is a cousin to each other. Therefore, you have 6 cousins in total."

WHAT? COME AGAIN? Somehow my 2 offspring and my 4 nephews/nieces become my cousins? WHAT? 

 

I know that the "T" in GPT stands for transformer, but transforming my gender, some basic arithmetic, and the lexicology of relationships seems to be taking things a tad too far!

AI and chemistry

 How good are AI generated responses to typical chemistry questions?

No better than the source material used for the answer ... which can include common misconceptions.

One such question is "What is the pH of water?". To a chemist this is a nonsense question (comparable to asking what colour an apple is or what shape a building is) yet it is often asked in school science classrooms around the world. 

I asked ChatGPT "What is the pH of water?" This was the answer ...

The pH of pure water at 25 degrees Celsius (77 degrees Fahrenheit) is considered neutral and is defined as 7. A pH value below 7 indicates acidity, while a pH value above 7 indicates alkalinity. It's important to note that the pH of water can be influenced by dissolved substances, and natural water sources may have varying pH levels due to the presence of minerals and other compounds.

I asked perplexity.ai "What is the pH of water?" This was the answer ...

The pH of water is 7, which is considered neutral. A pH of 7 is neither acidic nor basic. It is important to note that the pH of pure water can change due to the presence of impurities or the absorption of carbon dioxide from the air, which can make it slightly acidic. However, under normal conditions, the pH of pure water is 7, indicating neutrality

2

Surprise, surprise, both answers are inaccurate and riddled with common misconceptions (although, to its credit, perplexity.ai does provide sources, but to its discredit it does not refer to a specific temperature which is critical!). ChatGPT emphasizes "pure water", while perplexity.ai is content with just "water". To a chemist, both terms are the same, "water" is a pure substance. If water has substances dissolved in it it is no longer "water" it is an "aqueous solution". Perplexity.ai's referral to "normal conditions" is baffling, perhaps it refers to standard conditions for aqueous solutions? After these issues, both AIs seem to perpetuate the misconception that acidity, basicity (alkalinity) and neutrality are defined by a pH value. This is not true. They are two entirely different concepts (although both are based on an Arrhenius description of aqueous solutions). pH is a measure of aqueous hydrogen ion concentration, independent of whether the aqueous solution has been designated acidic, basic or neutral. Acidic, basic, neutral are terms to describe a the relative amounts of hydrogen ions and hydroxide ions in an aqueous solution.

So, let's start by talking about the neutrality of "pure water". Pure water is always neutral (regardless of its pH). This is because the concentration of acidic protons in the water, H⁺(aq) or H₃O⁺(aq), is always equal to the concentration of basic hydroxide ions in the water, OH^-(aq), that is [H⁺(aq)] = [OH^-(aq)]

An acidic aqueous solution is one in which the concentration of acidic protons is greater than the concentration of basic hydroxide ions, that is, [H⁺(aq)] > [OH^-(aq)]

A basic aqueous solution is one in which the concentration of acidic protons is less than the concentration of basic hydroxide ions, that is, [H⁺(aq)] < [OH^-(aq)] 

So "pure water" is always neutral, but what is its pH? pH is a measure of the concentration of aqueous hydrogen ions in solution, the greater the concentration of hydrogen ions in aqueous solution, the lower the pH. The concentration of these hydrogen ions is very much dependent on the water temperature. The pH of pure water at 10^oC is approximately 7.27 but the water is still described as neutral because [H⁺(aq)] = [OH^-(aq)]. The pH of pure water at 50^oC is about 6.63 but the water is still neutral because [H⁺(aq)] = [OH^-(aq)].

 The pH of water at 25^oC is approximately 7 and is based, NOT on it being defined this way, but on a calculation of the hydrogen ion concentration of water at this temperature.

So, what happens to pH if other substances are dissolved in water to form aqueous solutions at 25^oC? Using an Arrhenius definition of acids and bases (and a pH of 7 which has 1 significant figure but even that digit is uncertain), if an aqueous solution has pH < 7  at 25^oC it could be described as acidic, but if the temperature is greater than 25^oC the solution may be neutral, it may even be basic, we simply do not have enough information to decide. Similarly, If an aqueous solution has pH > 7  at 25^oC it could be described as basic, but if the temperature is less than 25^oC it is not a justifiable conclusion.

It is important to note that if there are dissolved "substances", including "impurities", "minerals" or "carbon dioxide", then the "water" is not "pure water", it is an aqueous solution, and the AI discussions are not relevant. Furthermore, some solutes dissolve in water at 25^oC and increase its pH  (aqueous solution of sodium hydroxide), some decrease its pH  (aqueous solution of hydrogen chloride), and some may have no effect at all on its pH (aqueous solution of sodium chloride).

There is no simple, correct answer for the question "What is the pH of water?". The question does not contain enough information in order for it to be answered. IF the AIs simply stated that the pH of water at 25^oC is approximately 7, that would be a pretty good response, however, by providing additional information in the answer they are repeating, and encouraging, common misconceptions about the nature of "pure water", "pH", "acidity", "basicity" (or "alkalinity") and "neutrality". 

For a discussion on why pure water is always neutral and why its pH varies, see https://www.ausetute.com.au/kw.html

For a discussion on what determines whether an aqueous solution is acidic, basic or neutral, see https://www.ausetute.com.au/abneutral.html

Excellent Advice for Chemistry Teachers

 The WA 2022 ATAR course examination report for Chemistry offers some excellent advice for all teachers of chemistry,

"Teach general concepts from first principles so that students can apply concepts to unfamiliar situations, not just write everything they know."

If you had shown this to me in 2019, I would have been shocked to think that any chemistry teacher wasn't teaching concepts from first principles, but COVID19 really did fundamentally change the way teachers were forced to teach, and how students were forced to study. "Remote learning" encouraged a return to the "bad-old-days" of rote learning "facts" and "how-to"s as a means to obtaining an end (success in exams). Unfortunately, once these electronic measures had been put in place (rather hurriedly in most cases), nobody seems to want to revisit this hasty construct and replace it with something better. There is a huge opportunity here to begin teaching chemistry as a science, using the scientific method, but no, we continue to teach students how to answer exam questions.

This is not education, it is training. And it is training of the worst kind since the ability to answer exam questions is not very useful in the workforce or in adult life.

Heed the advice, "Teach general concepts from first principles so that students can apply concepts to unfamiliar situations", and bad training becomes great education.

Making it harder to cheat

Here is the problem: teachers want to engage their students with interesting demonstrations and activities to motivate them to think about  a scientific concept. Students, on the other hand, just need a good mark on the tests and assignments so they can become a doctor, or a lawyer, a cobbler or a candlestick maker, etc.

As the technology available to students to help them answer their assignment questions gets better, teachers need to think about how to structure questions to make students think, rather than just google the answer.

Here is an example of a pretty standard sort of test/assignment question; What properties of aluminium make it suitable for use in cooking pots.  Give a disadvantage of using aluminium for pots.

If you copy and paste that into google, there are 2,090,000 results, and the top of the page will read, "Aluminum is lightweight, cheap and very good at distributing heat. It doesn't retain heat particularly well though, so the temperature will fluctuate as food is added to a hot pan. It's also the softest metal on our list, so it will scratch and dent pretty easily."

Assignment done! No thought required!

So we need to re-structure the question. How about this...

On the planet P42da, the element potsnpanium is used to make large pots in which the P42daians heat soup to above the boiling point of liquid water at 1 atmosphere. What properties of potsnpanium make it suitable for this purpose. Give an example of a safety precaution the P42daians should take when handling potsnpanium pots. Describe a way to reduce this hazard.

Copied and pasted into google this yields 0 results and a heap of useful suggestions:

"

• Make sure that all words are spelled correctly.
• Try different keywords.
• Try more general keywords.
• Try fewer keywords.

"

Might force some students to have a think about it.

Corrosion in the Kitchen

 There are two jars of nuts in the kitchen. One jar is always filled with unsalted nuts while the other jar is always filled with salted nuts.

Can you tell which jar holds the salted nuts?

Visit Corrosion Chemistry Tutorial (ausetute.com.au) for more information.

Cooking vs Chemistry

Chemistry is like cooking ... just don't lick the spoon.

Cooking can be used to help students understand fundamental chemical concepts, like chemical equations and stoichiometry.

Read how at https://www.ausetute.com.au/ausenews/ausenews.html

Vegan Leather

 My local bag shop is now full of bags that proudly state they are made out of "Vegan Leather".

Vegan leather? Surely that is an oxymoron?

    vegan = not consuming/using any animal products

    leather = animal skin that has been tanned or undergone a similar process.

So what is "vegan leather"?

It turns out that the majority or "vegan leather" is just poly(vinyl chloride) (PVC) or poly(urethane) (PU), polymers produced from reagents derived from fossil fuels. Handbags made out of PVC (vinyl bags) have been around for decades, and have been a much, much cheaper option than expensive genuine leather bags.Until now! By re-branding vinyl bags as "Vegan Leather" suppliers can increase the price, capitalizing on the significant consumer trend toward "vegan" products.

I live in a city that is trying to ban the use of single use plastic items including shopping bags and straws etc which end up in landfill and stay there for (not-quite but almost) ever. How do you feel about your new plastic "vegan leather" handbag? When it starts to fall apart (anything from about a month to a year or so depending on use and quality) and you throw it out, do you feel that you have done your bit for the environment?

If you live in a country where there are growing demands to reduce coal-fired power generation, and reduce the use of fossil fuels in cars etc, in order to reduce the community's "carbon footprint",  how do you feel about your fossil fuel based "vegan leather" bag?

It isn't "vegan leather". It is plastic.

vegan leather bag = plastic bag

Slime

One of the most popular school holiday "science projects" is to make slime by adding an aqueous solution of borax to PVA glue. Young children, and adults, can have hours of fun playing with this oozey slime, discovering some of its interesting properties along the way.

But what is slime and why should we be interested in it?

Read this edition of AUS-e-NEWS to find out more.

Subscribe to AUS-e-NEWS at https://www.ausetute.com.au/ausenews.html

Decline in Student Entrollments in Academic Subjects

 This fabulous graph of enrollments in the most popular HSC subjects over time was published in the Sydney Morning Herald today:

 

In the newspaper article, concerns were raised about the declining number of physics students, and the fact that only 22% of these students were female.

What I see in this graph is a general downward trend in enrollments of most of these subjects. You'd be particularly concerned about your future employment prospects if you teach Ancient History, for example.

What I don't see in this graph are any dramatic increases in enrollments, so, where have all the students gone?

Are overall student numbers declining (and hence enrollments in individual subjects are declining)?

Or, are there other less popular subjects with massive increases in student enrollment?

If we are concerned about the lack of females in Physics (22% female) why are we not equally concerned about the lack of males in Biology (36% male)? Or the poor showing of males in English Extension 1 (33%) and 2 (29%). 

We are still seeing student numbers divided along gender lines. So here are some "not-at-all-surprising" stats ...

• 5% of students in "Dance" are male
• 5% of students in "Textiles and Design" are male
• 8% of students in "Human Services" are male
• 10% of students in "Community and Family Studies" are male
• 5% of students in "Construction" are female
• 5% of students in "Electrotechnology" are female
  
• 6% of students in "Automotive" are female
• 9% of students in "Engineering Studies" are female
• 10% of students in "Software Design and Development" are female 

 And if I went back 30 or 40 years, I'm guessing the percentages would not be so very different.

What have we achieved in education in 4 decades?

Polymerize or Polymerise?

A polymer is produced when lots of monomers bond together. Monomer has Greek roots, mono meaning one and mer meaning parts. Polymer also has Greek roots, poly meaning many and mer meaning parts.

So  we can form a verb that means to produce a molecule of many parts. Because the words monomer and polymer have Greek roots, we should use the "ize" suffix, that is, polymerize. Yet, particularly in Australia,  the Latin "ise" suffix is used to produce the verb polymerise.

The word, polymerise, would have a Greek root (poly, many), a French root (mer, sea), and a latin suffix (ise). This would appear to suggest that to polymerise would be to make many seas. On the other hand, a monomer would be just one sea.

Merde!

Ionize or Ionise?

 In chemistry we have a verb to describe the process of producing ions, but how do you spell it?

Is it ionize? (rhymes with prize)

Or is it ionise? (rhymes with surprise)

The root of the word is Greek, so according to my school grammar teacher, the suffix should be "ize". The preferred IUPAC spelling appears to be ionize, and hence ionizing and ionization.

Similarly, we also have a verb to describe the process of producing atoms, also from a Greek root, so the preferred spelling should be atomize, not atomise. Hence we form the words atomizing and atomization.

I'm sure we'll continue to see the alternative spellings with an "s" rather than a "z" but they won't get you a Nobel Prise. Surprize!

Underwater Bubbles

 A backyard experiment you can do that will help you see Boyle's law in action.

https://www.youtube.com/watch?v=aHvGtWXTdso

 You will find more information in the feature article about SCUBA diving in the June 2022 issue of AUS-e-NEWS.

Let's Go SCUBA Diving

In 2021, Mitchell Goodwin, an experienced SCUBA diver, was diving off the coast of Mandurah in Western Australia. According to the report in the "West Australian", he descended to a depth of 42 m and stayed at this depth for 27 minutes. On his ascent, he made one decompression stop. When he got back to the boat he felt nauseous, lost his hearing, his sight, and blacked out.

What had gone wrong?

Read more in the June 2022 edition of AUS-e-NEWS.

Subscribe to AUS-e-NEWS, AUS-e-TUTE's free quarterly newsletter for chemistry students and teachers, at https://www.ausetute.com.au/ausenews.html

Periodic Table update

 IUPAC has updated the periodic table.

Time to update yours .... https://iupac.org/wp-content/uploads/2022/05/IUPAC_Periodic_Table-04May22.pdf

Australian Curriculum and Year 9 "Science"

 Last year I was writing questions for an Australian Years 9-10 Science textbook when I first came across the "gamma decay" problem.

The textbook authors stated that there are 3 types  of radioactive decay: alpha, beta and gamma (which is kind of OK for Year 9 or 10 science). They wanted to provide an isolated example of each type, that is, an example of alpha decay, an example of beta decay, and an example of gamma decay. Which is where the problem lies. Giving an example of alpha or beta decay is easy, just ignore any other possible radiations when you do it, which is the "traditional" method for teaching nuclear decay to Years 9 or 10, or indeed Year 11 chemistry (and yes, physics teachers are probably horrified, and rightly so, IMHO). But, you can't do this for gamma decay unless you want to talk about "excited states".

Which brings us to version 9 of the Australian Curriculum for Year 9 Science which states,

"describing in simple terms how different unstable isotopes decay such as radon-222 releasing an alpha particle, iodine-131 releasing a beta particle and cobalt-60 releasing gamma radiation to form stable atoms"

Alpha decay of radon-222 and beta decay of iodine-131 ... OK, can do.

Gamma decay of cobalt-60 ? Problem! Cobalt-60 decays by emitting a beta particle to produce an excited state nickel-60 atom. Excited state nickel-60 loses energy by emitting high energy gamma ray and relaxing back to a ground-state nickel-60 atom. But, we can't use this as an explanation because the introduction to excited states won't occur 'til, possibly, year 10 (when they do flame tests).

Has the Australian Curriculum been proof-read?

I think not. Further evidence of the writer's (or writers') slipshod approach to "science" is evidenced in this "interesting" extract (also for Year 9)

"investigating how radiocarbon and other dating methods have been used to establish that First Peoples of Australia have been present on the Australian continent for more than 60,000 years"

Problem 1: radiocarbon dating is pretty useless for anything older than about 40,000 years old, so it would be worse than useless for artifacts said to be 60,000 years old. 

Problem 2: where is the SCIENTIFIC evidence that Australia has been inhabited by humans for "more than 60,000 years"? Surely if you are going to make a statement like this, and force SCIENCE teachers to teach it, you need to support the statement, just a link a two, some references, to some SCIENTIFIC studies would be useful. 

So, here's what I think I know ... Mungo man/mungo woman are thought to be about 40,000 years old (give or take a few thousand). Blackened rocks at Moyjil are thought to be about 125,000 years old, but not linked to human habitation (that I'm aware of). The Pilbara petroglyphs have a wide range of dates depending on who provides them, but they also seem to be scientifically dated between 40,000 and 50,000 years. 

My problem is that I'm not an anthropologist, I know a little bit about chemistry (Chemical Sciences), a bit less about geology (sorry, Earth Sciences), even less about physics (AKA physical sciences), and practically nothing about biology (sometimes called a science), and hence I am NOT in a position to either a) know how long Australia has been inhabited for, or

b) to teach anything about this 

... and I suspect most SCIENCE teachers in Australia would fall into the same category.

AC: Australian Curriculum or Australian C_ _ p?

Converting Between Concentration Units

The concentration of carbon dioxide dissolved in water is about 0.000011 mol/L, while the concentration of carbon dioxide in blood is about 1100 ppm. It is not easy to tell which of these two solutions is the most concentrated because they are in different units. However, if we were to convert the concentration of carbon dioxide in water from mol/L to ppm, we could easily compare these two concentrations.

AUS-e-TUTE has just added a new tutorial, game, test, drill, prac, flashcards, quiz, worksheet wizard, and problem solving template to help!

 

Members should log-in to use these new resources: https://www.ausetute.com.au

 

If you are not an AUS-e-TUTE member you can view the tutorial for free at https://www.ausetute.com.au/concconv.html

Chinese Milk Scandal

 When we buy food from a shop, we assume that food is safe to eat, but sometimes it isn't!

In 2008 six babies died from kidney stones and an estimated 54,000 babies were hospitalized in China after being fed "Infant Formula" (baby milk) adulterated with melamine, an industrial chemical. It is thought that about 300,000 babies in total were affected by what came to be known as the "Chinese Milk Scandal".

Why was melamine added to Infant Formula? And why did it take so long to discover its addition?

Read more in this edition of AUS-e-NEWS:

Subscribe to AUS-e-NEWS at https://www.ausetute.com.au/ausenews.html