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

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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.