Adrian Dingle’s Chemistry Pages - The Blog

Subscriber Updates - Worked Answers 2009 - REMINDER

2009 Worked Answers (Drafts) have now been added to the relevant subscriber areas.

Subscriber Updates - Worked Answers 2009

Expect 2009 Worked Answers to be added to relevant subscriber areas within 72 hours.

Applied Practice AP Chem series Book #10 (Acids and Bases) is now finished

Books #10 should be available fairly soon, here;  http://www.appliedpractice.com/index.php?module=shop&cat=78

Subscriber Updates

Updated AP Worked Answers for the following are now in the relevant subscriber areas;

2002, 8; 2004, 2; 2004, 3.

Hand-holding on the AP exam reaches new levels

I’m beginning to wonder where it’s all going to end. With the event of the new equation writing format in 2007 I was not surprised (but nevertheless disappointed) to see that there was a new level of hand-holding for the candidates on this question. You will recall that ridiculous hints (like, “an oxidizing agent”) were added to some questions in a manner that they never had been in the past. Previously a candidate had to recognize the chemical in question was an oxidizing agent. Anyway, I was prepared to run with it in an attempt to give the CB the benefit of the doubt, but now that we have seen these overwhelmingly excessive hints three years in a row, it’s now time to call it as I see it.

I feel that this question is becoming close to invalid - yes, I’d go that far. It will start to fail to discriminate between good and bad candidates.

Of course, question #4 is the most obvious place that one sees this hand-holding, but there are lots of other examples too.

Consider this comparison from 2007 and 2003.

Question 1 in 2007 parts (c), (d) and (e) dealt with a reaction between HF and hydroxide ions. Here’s how it was set-up.

1. It gave the equation for the reaction between HF and and the base.

2. It TOLD the candidates to calculate the moles of HF remaining in solution, i.e. it TOLD the candidates that there was a limiting reactant.

3. It TOLD candidates to calculate the concentration of salt produced (a step needed for 4. below), which is a step the candidates used to be asked to work out was necessary for themsleves.

4. It asked candidates to find the pH of the solution, i.e apply find the pH of the buffer.

By giving SPECIFIC pointers (and points) by asking the questions separately, the questions were basically TELLING the kids that this was a buffer problem, and walking them carefully through the steps, but compare that to say, 2003 question 1 (c), where;

1. The equation for the reaction betweeen aniline and HCl is NOT given.

2. The reaction is not flagged as a limiting reactant problem so you had to work that out for yourself, and therefore you had to realize that it was a buffer.

3. A separate step was NOT included to flag the necessity for calculating the concentration of the salt.

4. The pH calculation was part of the whole question and the process was not broken down into individual steps.

As I say, there are plenty of other similar examples to the new level of hand-holding.

More 2009 Exam Comments

Following my original thoughts on the 2009 (at the first link here; http://adriandingleschemistrypages.com/AdrianDinglesChemistryBlog/nfblog/?p=198), I wanted to add the following thoughts.

Question 2:

The use of torr seems to have upset a few people. It doesn’t bother me in the slightest since the conversion has always been included in the data packet, HOWEVER I AM confused by the reaction to this in some circles for this reason; it’s strange how torr would upset people, when, in the past, people are quite happy to let the ancient nomenclature of acetic acid usurp the more useful (and modern) nomenclature of ethanoic acid - that makes NO sense to me.

We need a separate lab exam if we are to test lab skills. PERIOD.

Question 3: 

My angst at fractional orders showing up is based purely in the non-descriptive nature of the course description. I’ve been speaking and writing about this for years and if you would like to know more take a look at this document -http://www.adriandingleschemistrypages.com/gisa.pdf In a nutshell, a more prescribed syllabus is ABSOLUTELY necessary for a standardized test since it shows one what can and can’t be on the exam. Most American teachers make the mistake of thinking that a heavily prescribed syllabus dictates what you do in the classroom - nothing could be further from the truth - http://www.rod.beavon.clara.net/salisbur.htm

Question 4:

The general ease of the net ionics of late, coupled with the RIDICULOUS hints (”reduced completely” (2009), “decomposes” (2009), “forming a complex ion” (2008), “oxidized” (2008), “an oxidizing agent” (2007), “a reducing agent” (2007)) being included is beginning to invalidate this question completely in my opinion.

2009 AP Worked Answers and 2009 Exam Comments

Here they are in DRAFT form. Comments encouraged and please point out my errors!

2009 Exam Comments

2009, 1

2009, 2

2009, 3

2009, 4

2009, 5

2009, 6

2009 Worked Answers will appear in the Blog tomorrow (5/14/09)

Look out for my Draft, 2009 AP Worked Answers here tomorrow. As usual they will be around for a very short time.