Technical Problem Solving C

[Flavorflav]

Here's an interesting question that zero out of 20 teams got completely correct at CWRU yesterday:

For a general heat exchanger, consider the inlet temperature of chamber A to be T1A, the outlet temperature of chamber A to be T2A, the inlet temperature of chamber B to be T1B, and the outlet temperature of chamber B to be T2B. If T1A > T1B, is it possible that T2A < T2B? Why or why not?

Many teams had the right answer (yes), but none were close to an explanation as to why. Just thought I'd put it up here to challenge you guys and make sure I wasn't being unfair.

In a countercurrent exchanger where T1B is much lower than T1A, T2A would always have to be higher than T1B, but there is no reason that it would have to be higher than T2B. I'm not sure that counts as an explanation, though.

[ichaelm]

Exactly! I was looking for something about countercurrent heat exchangers, or really anything besides concurrent flow.

[solakmagic]

Hey all! I was wondering if anybody had a good resource/ method for equivalent weights in Faraday's 2nd Law of Electrolysis??

[AlphaTauri]

So this is only really tangentially related to TPS, but I thought it might have some impact on future years...

We've started our electrochem unit in AP Chem, and it turns out that the Nernst equation, which I thought was pretty standard electrochem from doing TPS, is apparently "beyond the scope" of the new AP Chem curriculum... as is the Henderson-Hasselbalch equation, which is incredibly common when dealing with acid/base stuff (other "exclusions" can be found here). I do see their point in removing material so that the course focuses more on depth than breadth, but cutting things like Nernst and H-H seems... excessive. Mostly it's just odd to think that for future sciolyers, these concepts that are standard knowledge now won't even be covered in class.

Thoughts? Opinions?

[fishman100]

So this is only really tangentially related to TPS, but I thought it might have some impact on future years...

We've started our electrochem unit in AP Chem, and it turns out that the Nernst equation, which I thought was pretty standard electrochem from doing TPS, is apparently "beyond the scope" of the new AP Chem curriculum... as is the Henderson-Hasselbalch equation, which is incredibly common when dealing with acid/base stuff (other "exclusions" can be found here). I do see their point in removing material so that the course focuses more on depth than breadth, but cutting things like Nernst and H-H seems... excessive. Mostly it's just odd to think that for future sciolyers, these concepts that are standard knowledge now won't even be covered in class.

Thoughts? Opinions?

I knew that they removed the Nernst eqn but I didn't know that they also removed H-H. It's true that they may be "unnecessary" since the new AP Chem emphasizes depth, but I'm glad we learned about them because when it comes to FRQ's (and even some MC questions) I found them to be extremely helpful in explaining/calculating pH. In fact, one of our FRQ's on our test required using H-H...
I'm wondering if students who use either equation will receive credit on the AP exam.

[Crazy Puny Man]

So this is only really tangentially related to TPS, but I thought it might have some impact on future years...

We've started our electrochem unit in AP Chem, and it turns out that the Nernst equation, which I thought was pretty standard electrochem from doing TPS, is apparently "beyond the scope" of the new AP Chem curriculum... as is the Henderson-Hasselbalch equation, which is incredibly common when dealing with acid/base stuff (other "exclusions" can be found here). I do see their point in removing material so that the course focuses more on depth than breadth, but cutting things like Nernst and H-H seems... excessive. Mostly it's just odd to think that for future sciolyers, these concepts that are standard knowledge now won't even be covered in class.

Thoughts? Opinions?

I really do not like some of the new curriculum changes. They scrapped most everything that has to do with logarithms - Nernst, H-H, Arrhenius, Clausius-Clapeyron (did I spell that right? xD). I don't think they scrapped the kinetics equations - like, for zero/first/second-order reactions. Idk about that.

They also got rid of phase diagrams, with the justification that phase diagrams are covered in a first year chemistry course, or what-not

Lots of things are covered in a first year chemistry course, that's not a good justification to get rid of phase diagrams from the AP curriculum

But yeah, not pleased with that at all :/ CollegeBoard...

If what happened with AP Bio ends up happening for AP Chem (Bio's curriculum got easier, but had WAY less 5's - so basically CollegeBoard could make the exam easier, get more kids to take it, and keep the average score the same so they can technically say that the curriculum is still the same difficulty)...then...

What do you guys think?

[darkwinters]

Has anyone run into any thermodynamic stuff on tests that hasn't had to do with Newton's law of cooling?

[alwaysmatts]

Hey so i decided to do tps next year(if they still have this event)

According to this year's test(or the previous years'), is everything for each topic covered in AP, or it goes deeper than that?

If so, whats a good source for study

[Unusual Flux]

Has anyone run into a problem regarding the Stefan-Boltzmann equation before?

[anitawood]

Does anyone know the subjects for Technical Problem Solving for the 2015 season? I know some schools already have draft rules for the 2015 events. Thanks.