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Sorry, a couple more topscore Q's....

Discussion in 'Pre-Dental' started by portlander, Aug 18, 2002.

  1. portlander

    portlander Member
    7+ Year Member

    Jun 18, 2002
    Likes Received:
    I hope someone else is learning from my lack of knowledge too...

    Here it goes...

    1) Which of the following atoms have an expanded valence shell and form compounds with five of more valence electron shells?

    I. S
    II. Si
    III. N
    IV. Br

    A. I & II
    B. I & III
    C. I, II, & IV
    D. II & III
    E. IV only

    The answer key says 'C'. I was pretty confident that halogens RARELY exceeded four bonds, and that N basically never had more than an octet. Is the answer right, or is this a useless question?

    2) Aniline and benzoic acid were disolved in 50ml of diethyl ether and transferred to a sepratory funnel. To the funnel was added 50ml of 0.5M HCL. What is the distribution of the 2 compounds?

    A. Aniline is in the aquous layer, benzioc acid is in the ether layer.
    B. Aniline is in the ether layer, benzoic acid is in the aquous layer.
    C. Both are in the ether layer.
    D. Both are in the aquous layer.
    E. The distribution cannot be determined.

    The answer key says 'A'. I don't know why. I thought that benzoic acid would be immisible in ether (no hydrogen bonding in ether). I got an 'A' in organic lab---I should know these things!!

    Thanks for all your help in advance. This forum is a GREAT resource.

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  3. ddasung

    ddasung Junior Member
    7+ Year Member

    Jul 22, 2002
    Likes Received:
    i think the answer to the first question is wrong on topscore. i believe it is si and s that can expand their octet due to the presence of d subshell. but, need a confirmation from someone.

    i can help you with the second one. the key is that it is in acidic condition, HCl. this means that you will protonate anything that is basic, and in this case aniline can be protonated and confer a + charge. benzoic acid is an acid already and it would be affected in the acidic condition. the positively charged aniline will mingle with water and stay in the aqueous layer and on the other hand the benzoic acid will be found in diethy ether layer.

    hope this helps.
  4. tinker bell

    tinker bell 1K Member
    7+ Year Member

    Oct 18, 2001
    Likes Received:
    I know for sure that the answer to the first question is wrong. My princeton instructor confirmed this with us. So, you are all the right track.
    Happy studying

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