<p>How was Nationals?
Remember not to discuss specific problems until the 26th, just "refer" to them.</p>
<p>Also, does anyone know the weight of each of the three parts? Because there's a rumor the lab is worth little which would be reassuring.</p>
<p>I just got back from it. I did poorly.</p>
<p>I took it yesterday, too. I thought it was the hardest it’s ever been in the history of national exams. ■■■.</p>
<p>@sic_infit:
I’m guessing that each part is equally weighted, but I know for a fact that they won’t even score the Parts II and III if you don’t make the top 150 scorers on the Part I MC (which I know for sure I did not)</p>
<p>
</p>
<p>How did you determine this? Anyhow, I found the multiple choice to be very difficult. Even though my preparation was confined wholly to my review on the way there, I expected to do slightly better.</p>
<p>ARG. I didn’t even see problems 51-60. I’m dead. And I definitely (almost) aced Part III. 
Ah well, more time to study :D</p>
<p>Well, I wish I had known that about Parts II and III if what you say is true; I could have gone home after Part I. :)</p>
<p>@Silverturtle
I learned it from a USNCO coach who sent one of his students to IChO and was an Olympian himself.</p>
<p>yeah I took it yesterday…so hard! the labs were impossible! but I looked up how to do the second one online and i was sort of close…sort of.</p>
<p>Now that the testing period is over, how did everyone do?</p>
<p>Also, feel free to discuss specific problems if you want.</p>
<p>Only four students took the national test in our area. My daughter felt pretty good about it until the drive home when she realized she brainfarted on part of the free response kinetics problem and also guessed wrong on the highest oxidation state of vanadium. There were also a handful of multiple choice questions where she had to make educated guesses. She was hoping to make the top 50, but she doesn’t think she’ll get there.</p>
<p>It was tough. I did decent on Part I and Part II, and bombed the labs, but that was expected</p>
<p>The exam was comparable in level than some previous years (except the lab), but there were several tough problems. Coordination chemistry for one of the labs was unprecedented.
I still can’t figure out whether sulfur’s ability to form S8 comes from its d-orbitals or because its 3p orbitals are relatively flexible compared to the tightly held 2p orbitals of oxygen (thus allowing for more bond lengths and bond angles). The pre-exponential factor comparison between ozone and nitrous oxide still mystifies me (it is because correct orientation is more difficult in one of the species?)</p>
<p>I was hoping for harder organic. The vanadium problem, however, was really nice. </p>
<p>Good luck to everyone!</p>
<p>For the S8 thing, I said your second reason but I kinda bs’d that explanation. I think the Sulfur/Oxygen one was the hardest FRQ. For the pre-exponential factor, I’m pretty sure the second reaction has a smaller A, since to form NO2, the NO has to hit the N2O molecule on the oxygen atom, which only happens in a fraction of the collisions, whereas in ozone, any collision will abstract an oxygen molecule. And for the Vanadium problem, my oxidation states in order were: +5,+2,+3,+4.</p>
<p>Did anyone have any trouble identifying the metal salts in the coordination chemistry lab? It seemed to me that the color of each salt should have been a dead giveaway, but I don’t know if everyone felt the same way.</p>
<p>Forming a complex with Fe(III) and oxalate is one of the AP Chem labs. Cobalt and ammonia is another, but it’s hexaminecobalt (III), and if I heard right, the USNCO lab had Co(II).</p>
<p>I identified the original salts correctly, but I think on a couple of my newly formed complexes, I had the wrong number of ligands and geometry. If anyone wants to discuss the test in more detail they can PM me too and we can talk on AIM or something</p>
<p>How many on the MC is usually enough to be top 150?</p>
<p>I qualified, but I couldn’t go because of some very poor choices a family member of mine made.</p>
<p>No offense to Ninja, but I don’t believe for a minute that the top 150 are determined solely by the MC. The free response questions do a much better job of showing what you know, and if Ninja is right, those don’t count for squat in terms of making honors or high honors. I can see where they’d have some kind of cutoff on the MC beyond which they don’t grade the FR or Lab, but it wouldn’t be the top 150. And since there are only 60 questions, the 150th spot is probably an n-way tie, with m additional students tied for the next spot for having missed one additional question.</p>
<p>But in answer to Programmer’s question, to quote the owl on the Tootsie Pop commercial, “the world may never know.” They don’t report scores on the National MC the way they do on the local test, they just tell you how you did in each of the ten subject areas compared to other test-takers: Below Average, Average, Above Average, or Exceptional. You never find out how many you got right or wrong in each category, and if I understand correctly, you never get any scoring information of any kind on the FR or Lab.</p>
<p>Hey
Im new to this forum, and just took the chemistry olympiad national exam in California on Sunday. Thought the first lab was kinda hard, the second one was easier. The multiple choice was the hardest one in the last 10 years, and the FR was about medium difficulty (my opinion). </p>
<p>Im thinking I might have done like 55-57 on MC, 90 on FR, and Average on Lab. </p>
<p>What do you guys think the cutoff for MC, FR, and Lab will be this year?</p>
<p>Also, I read online in the Coordinator’s handbook that they will start calling Monday, May 3. Do they usually start on this date, and how long does it take them to call all twenty?</p>
<p>Thanks</p>
<p>Has anyone heard anything yet?</p>