UTC: Sunday, October 22nd, 2017

Summary of additions to new AP Chemistry curriculum – PART #2. Mass Spectrometry

This is the second in the series (the first is here) of short blog posts on the new content (as I currently see it) of the 2013-14 AP Chemistry Curriculum.

Mass Spectrometry (at this level) is something that I know a little bit about. Now, although that statement in and of itself is accurate, like all of these posts about new content, I’m still only able to speculate about how it might manifest itself in the new AP exam. As such, please proceed with caution!

So how do I know about this stuff? Well, this has been on the English A Level and IB Chemistry exams for decades. As such, through my experience of teaching both of those courses quite extensively, I’ve seen how they handle it. At the moment, i.e., in the absence of any other information, I think its reasonable to assume that the AP will do something very similar – we’ll see.

Actually when reading the framework document, it would appear that the scope in the new AP in terms of this topic is really quite narrow. In the first instance it would appear to be limited to knowing that Dalton’s atomic theory had to be modified to account for isotopes, and that modern mass spec data provides evidence for the same. Secondly I would expect some simple interpretation (and maybe simple calculations*) based around some elemental mass specs. The relevant sections of the framework document are; Enduring Understanding 1.D, Essential Knowledge 1.D.2 a-c and Learning Objective 1.14.

*The framework says students should be able to ‘estimate’ average atomic mass from spectral data so perhaps specific ‘calculations’ are out.

Reading the curriculum framework document as is, does not lead me to believe that the inner workings of a mass spectrometer is on the table, although I suppose I might change my mind after seeing the new course description or some sample questions.

So what about the interpretation of these spectra? Well, I see no point in going beyond pointing to a few example questions from the A Level and IB courses to give a feel of what I think is likely. Here we go.

This is a question from the May 2001, IB Chemistry HL, Paper 3 – Option G.

IB Chem, May 2001, HL, Paper 3

IB Chem, May 2001, HL, Paper 3You can find the answers to this question, here.

Here’s a hybrid question (between analysis of spectra and the workings of the machine) from AQA, Unit 1, January 2004, where I would think part (d) would definitely be in play (with the caveat above about estimates versus calculations).

AQA, Unit 1, January 2004You can find the answers to this question, here.

Finally, here’s something from Edexcel January 2009, Paper 1, about the workings of the mass spectrometer that seems (currently) much less likely to be relevant.

Edexcel January 2009, Paper 1You can find the answers to this question, here.

As I have been at pains to point out, this remains speculation at this point but as of know these are the assumptions that I am working on.

Comments

  1. I can’t imagine that they would ask questions about the actual workings of the mass spectrometer. Frankly, I don’t know the answers to most of those questions myself. The first question, though, about interpretation of the spectra, seems reasonable to me, and even probable. Part D of the second one is reasonable, and none of the third one. I certainly hope that I am correct about this. I am pretty confident that I am.

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