Initially written by our staff member llamachemist (Anugrah Chemparathy, 2020 IChO gold medalist, we have tried to preserve the guide as it has initially been written. You can look at the original source here.
This advice is only relevant to people who can comfortably solve every problem on a pre 2017 USNCO (and most of the newer ones!) or have done all the past USNCOs (locals and nationals). If neither of these are true, then you should return to this document at a later time.
In my opinion, almost all of the non recent USNCOs are boring. Especially in your second year of preparing for the Chemistry Olympiad, you’ll want to find a new way to learn. Here is my not very hot take: reading anything beyond Atkins/Zumdahl + Klein1 is completely unnecessary for USNCO (it's not a hot take because everyone agrees with me). Even to get into IChO, you don't need anything more than Atkins/Zumdahl + Klein + chapters 27-38 & 40 of Clayden2.
I really don't understand why everyone keeps buying copies of Atkins Physical Chemistry, Housecroft Inorganic, or Voets Biochemistry to prepare for USNCO or IChO when a simple glance at the contents of either will make it incredibly obvious how useless they are for both IChO and especially the USNCO. Even for the most specialized topics at IChO, you’re better off learning them from online (ex. ChemLibre) than in a textbook. By the end of my senior year I had spent more time reading physics textbooks (just for fun) than I had chemistry textbooks. Here is a quote from a noted Russian IChO gold medalist:
R: I didn’t buy a book to prepare for the Olympiads except for Albert L. Lehninger’s works. There are plenty of resources online.3
The real secret to succeeding (in the Chemistry Olympiad) is to build your problem solving ability. The best way to do this is to practice solving challenging problems. Over the years I did a lot of problems. Here are my opinions on some of the problems I did, and some of the problems I did not do.
Note that what I’ve listed below is pretty brief and not necessarily a full endorsement or indictment of certain years of problems. My biggest piece of advice is to look through all the problems (not just the ones I’ve listed in each year's description, and PICK WHAT LOOKS INTERESTING. I didn’t list every single problem I liked since that would take forever, so don't stick to this list! And also don't try to meticulously do all of them. That's a waste of time.
One more time: I do not recommend you try to grind all of these problems. You will burn out (source: been there even though I did just a fraction of them). Just do what seems interesting.
IChO Preparatory Problems are great for practice. Here are some recent years sorted by how interesting/difficult I think they are in general (not counting organic which varies in quality/difficulty).
2013 - infamous Russian IChO with very hard questions. Generally not applicable for USNCO. The few that I would recommend: #8, 9, 13, 15 although they are just as difficult as the rest (but mildly more applicable to USNCO/common IChOs)
2015 - Another infamously difficult year. None of these questions are really helpful for USNCO. Don't waste your time on them until you are preparing for camp.
Of course take this advice with the commentary given at the top of the page: look through anything you want and do questions which interest you. Don't try to adhere to the questions listed here and end up getting stuck in a grind.
Some olympiads from other countries have good quality questions. Here are links to some of the famous olympiads along with my opinions of them.
- Except for the organic, these are almost all easier than USNCO
- Generally around USNCO level although these questions are usually much less creative. (The organic is much harder than USNCO of course)
- Don’t do these unless you’re very experienced (like at the end of the year, or maybe when you are a returning camper) - Organic and Biochemistry have no relevance to USNCO. - Inorganic is usually much beyond USNCO difficulty, but generally very fun. - physical chemistry is usually boring bashing(although occasionally there are some good ones) of some random equation or data they give you and frequently easier than USNCO. These questions are often soul sucking. 0/10 would not recommend. - Analytical difficulty varies a lot. Some of them are extremely easy, while others are very interesting and bring added problem solving to ideas which are useful for USNCO (see 2015 Tour 1 #4). These questions can be extremely challenging, but if you are already well versed with USNCO, I think that they are good exercises in problem solving.
- Recent: [https://olympiads.hbcse.tifr.res.in/how-to-prepare/past-papers/](https://olympiads.hbcse.tifr.res.in/how-to-prepare/past-papers/) - Old: [Pre 2008](https://chem.hbcse.tifr.res.in/indian-national-chemistry-olympiad-2002-2007/) - Generally these questions are either easy or impossible due to being extremely weird. I don't really enjoy them, but some of them could be acceptable for USNCO practice (2002 #5, 2003 #1)
Some of the IChOs are good, and some of them are bad for USNCO practice. Here’s a summary of my thoughts on some of them.