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IChO 2008 Preparatory Question (Updated)

May 21, 2008

I have downloaded a copy of preparatory question for IChO 2008 out of curiosity. The question can be found here:

Answer is not provided on site, hence I have to do some self-research online. So far I have just gone through question 1 and 2.

On Q1:

I wonder if this is Sir Arthur Conan Doyle original work? Apparently Sherlock Holmes has a more in-depth knowledge on chemistry than his partner, Dr. Watson…

At first glance the chemical substance looks like group 1 element—vigorous reaction with water, stored in paraffin oil, produce an alkaline solution when dissolved…

But the calculation goes wrong. If 2 mol of the substance produce 1 mol of hydrogen, then the R.A.M. of the substance is 4. (lithium is 7)

I try to overcome this problem by presuming the substance as Lithium Hydride, but this time the calculation for the 2nd part goes wrong. If the final salt product is XF then the R.A.M. of X is 9! (Beryllium)

On Q2:

Perhaps the most important clue given here is intermediate I. There aren’t many metal chloride that exists in liquid form. My best guess for H is antimony, and for I it will be either antimony pentachloride or trichloride.

I have downloaded a book on antimony via google book search. Hopefully it will provide more hints.

UPDATED: IChO website has provided the work solution. Seems that my guess for the first question is half correct…since I didn’t consider isotope of lithium and hydrogen. Answer to the 2nd question is vanadium, much to my surprise.

2 Comments leave one →
  1. June 8, 2008 1:49 am

    you’re plain amazing for putting technical details of academic stuff in your blog. Lol.

  2. October 18, 2013 4:06 pm

    Fine way of describing, and pleassant post to take facts on the topic of my presentation
    topic, which i am going to convey in college.

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