Search results

I think the teacher asking the question thought all six would be liquids. I think the teacher didn't consider just how dangerous ethanoic acid that is water-free or even glacial actually is, nor that it will solidify if cooled down to about 10 degrees C. Ethylamine is meant to be a liquid in...

graphical

So, in this case, any of the three methods will work, though I would go with elimination from a first glance.

I don't entirely agree because I see what is "useful" in chemistry as much broader than the specific methods and techniques that a practicing chemist carries out on a day-to-day basis. I believe that learning chemistry is about far more than knowledge of chemical facts and techniques. It is...

I agree, you are free to choose a method if one is not specified... but if one is specified, you are required to use it.

Assuming the question means that Adrianna sleeps for 7.5 h (ie 450 min) and her pulse is 56 (ie. her heart beats 56 times per minute), then \begin{align*} \text{Number of heartbeats while sleeping}\ &= 56\ \text{beats per minute}\ \times 450\ \text{minutes} \\ &= 25,200\ \text{beats} \end{align*}

In general, I agree. I don't mind asking questions on unfamiliar chemistry - I asked about the exact tautomerisation that is relevant to your example, after all - but I wouldn't ask the question seeking the incorrect answer. Hydration of alkynes can't reasonably be asked unless tautomerism has...

I am hoping to see comment on the linearity at high concentration, but also noting that there is a large amount of cadmium being detected, even if the accuracy of the calculated concentration is open to question. One of the possible areas for comment on improving the investigation will be what...

As many of you are probably aware, I have begun a discussion of the 2021 BoS chemistry exam, and I thought I'd start one for the MX2 paper as well. For those who have not seen the paper, Trebla has posted it at...

For those interested in the hardest / easiest MCQ, you might be surprised to learn that, if I look at questions 1 and 2, one of them was answered correctly by almost twice as many students as the other... so one of them was one of three easiest questions, and the other was in the five most...

Good point, it does mean that there was a reminder that Q18 could not include silver as one of the three cations... but I don't think it advantaged too many students, given that Q18 was one of the 8 questions answered incorrectly by the majority of students who sat the exam.

Yes, but I am looking for the issue being raised being recognised in the next part, and that can be done with or without considering boric acid itself

There were quite a few places where one part of a question would provide support for the next... perhaps not as well as I intended, though

You can't polymerise vinyl alcohol because it exists almost entirely as acetaldehyde, as the preceding question / calculation proved. However, you can polymerise vinyl acetate and then hydrolyse the ester groups to produce polyvinyl alcohol.

Thank you. I wouldn't say "insanely difficult" but it is certainly a challenge. It does help to have a very strong knowledge of chemistry, the HSC, and education. :)

On Q27, that's an excellent point about linearity in the 0-2 ppb range. I am looking for a comment on linearity as far as extrapolating to give the highest result, but I hadn't noticed that the same issue may arise at the low concentrations. The question was meant to stimulate consideration of...

First, it's great to see an active discussion of the paper. :) To pick up on a few topics... Q11. I've seen different guidelines on what is needed for effective buffering. If you take the view that you need the ratio of the conjugates to be between 10:1 and 1:10 then buffering is present...

No HSC student will be given sodium metal to use. The fact that acids react with sodium is part of the year 11 course, so they should realise that sodium metal plus an organic substance producing CO2 can be a carboxylic acid or an alcohol. They hardly touch reduction, so reaction of a carbonyl...

Thanks for the comments. I'll refrain from commenting on them all until I publish which were the easiest and hardest questions, but for now: Q1: I was pleased that this did not trick as many students as I expected. Q7: Anion testing in module 8 is restricted to a set of specified anions and...

I'm not commenting while I wait for others to offer suggestions, but I am interested in what was seen as difficult too. And, just as a teaser, and considering answers I've received by DM as well, two of the three questions with the highest correct rates have yet to be mentioned.