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Topic: 1st problem IChO  (Read 4303 times)

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Offline Rutherford

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1st problem IChO
« on: January 31, 2014, 08:49:07 AM »
May someone check whether the solution for the fourth part of problem one is 123°: http://icho2014.hus.edu.vn/document/01-24-2014%20IChO46-Preparatory.pdf as I am suspicious?

Offline CrazyAssasin

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Re: 1st problem IChO
« Reply #1 on: January 31, 2014, 08:47:10 PM »
Well, I'm not sure about my answer, but I got 102,5 degrees.
 It is nice to know that there are some people, like you, who are already analysing preparatory problems. If you wish, we could discuss about other problems too.

Offline Rutherford

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Re: 1st problem IChO
« Reply #2 on: February 01, 2014, 03:06:58 AM »
Of course I wish.
Your answer seems more reasonable, so I would like to get through this one first. What values did you get for the dipole moments of OH and OMe bonds? I got 1.51 and 1.12 respectively.

Offline curiouscat

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Re: 1st problem IChO
« Reply #3 on: February 01, 2014, 03:36:18 AM »
May someone check whether the solution for the fourth part of problem one is 123°: http://icho2014.hus.edu.vn/document/01-24-2014%20IChO46-Preparatory.pdf as I am suspicious?

I got 123 too.  So I suppose we made the same mistake. :)

Nice problem.
« Last Edit: February 01, 2014, 03:54:20 AM by curiouscat »

Offline Rutherford

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Re: 1st problem IChO
« Reply #4 on: February 01, 2014, 03:40:13 AM »
;D. Maybe it's so big because the assumptions are bad.

Offline curiouscat

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Re: 1st problem IChO
« Reply #5 on: February 01, 2014, 03:50:13 AM »
What values did you get for the dipole moments of OH and OMe bonds? I got 1.51 and 1.12 respectively.

I did too.

Offline curiouscat

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Re: 1st problem IChO
« Reply #6 on: February 01, 2014, 03:53:23 AM »
;D. Maybe it's so big because the assumptions are bad.

Ok. Found one mistake. Now I get 101.7°

Did you forget to square 1.69D in the resultant?  ;)

What's the official answer. My chemistry is too bad to remember any more what the textbook angle's supposed to be.  ;D

Offline Rutherford

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Re: 1st problem IChO
« Reply #7 on: February 01, 2014, 05:26:32 AM »
Yep :-[. Got now almost the same answer as you 101.6°, but the difference probably arises because of rounding.

Offline curiouscat

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Re: 1st problem IChO
« Reply #8 on: February 01, 2014, 05:27:36 AM »
the difference probably arises because of rounding.

Indeed.

Offline Big-Daddy

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Re: 1st problem IChO
« Reply #9 on: February 01, 2014, 10:33:16 PM »
Can you show your working? Did you have to use the C-H dipole moment given in part iii), and what dipole moments did you get for O-H and C-O?

Offline Rutherford

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Re: 1st problem IChO
« Reply #10 on: February 02, 2014, 03:33:17 AM »
No. I wrote the result for individual dipole moments in my second post.

Offline Big-Daddy

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Re: 1st problem IChO
« Reply #11 on: February 02, 2014, 11:58:51 AM »
Ok, silly mistake on my part. I got 101.7(537)°, so roughly 101.8°. Must be rounding again.

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