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    pop000's Avatar
    pop000 Posts: 352, Reputation: 6
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    #1

    Jan 24, 2011, 01:05 PM
    1)Solubility In Water. 2) optical activity
    tow question:
    1) in the picture you can see 4 Different group of Molecules, I need to Decide Which group all the Molecules in it are Solubility In Water. I think is group D. I know that what would make a molecule insoluble in H2O is they need to be Polarity like water, and they also need to have an Hydrophile Feature. Ithink the answer is D

    question 2) in this list I need to say Which Molecule can have optical activity.
    I think is Molecule D
    A)CH2ClCH=CHCH3
    B)CH3CHCl2
    C)(CH3)2CHCH2CH(OH)CH3
    D)CH3(OH)C=CHOH
    tell me please if I correct.
    thanks.
    DrBob1's Avatar
    DrBob1 Posts: 425, Reputation: 86
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    #2

    Jan 24, 2011, 04:10 PM
    POP: Your answer to your first question is correct; all the compounds in D are soluble in water. One compound in each of the groups is not soluble. Your answer to question 2isincorrect, however. If you look, only compound C has an asymmetric carbon atom - one that has four different groups attached to it. Compound D has 3 C atoms. Carbons 1 and 2 have only three groups attached because of the double bond; Carbon 1 has three H atoms. Compound D is an unusual choice for a question like this because it is not stable (it is an ENOL - a compound with a hydroxy group (OH) on a doble bonded carbon. This willrapidly isomerize to either of two alternatives: Hydroxyacetone (CH3COCH2OH) and 2-Hydroxypropanal (CH3CHOHCHO). The latter compound does have an asymmetric carbon but the isomerization will cause the loss of optical activity (racemization). So, it could have optical activity, but not as shown.

    Sorry for the typos in the answer, but somehow I have ended up in typeover mode and I can't add a spaceor a new letter.
    Unknown008's Avatar
    Unknown008 Posts: 8,076, Reputation: 723
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    #3

    Jan 24, 2011, 11:48 PM

    For 2, draw each molecule to help you :)

    Press the Insert button on your keyboard DrBob :)
    pop000's Avatar
    pop000 Posts: 352, Reputation: 6
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    #4

    Jan 25, 2011, 01:56 AM
    Comment on Unknown008's post
    Hi. Well I tried to draw but I am not so good in draw things. :)

    Thank you.
    pop000's Avatar
    pop000 Posts: 352, Reputation: 6
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    #5

    Jan 25, 2011, 02:23 AM
    Comment on DrBob1's post
    Great answer really thank you DrBob1 :-)
    Unknown008's Avatar
    Unknown008 Posts: 8,076, Reputation: 723
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    #6

    Jan 25, 2011, 04:26 AM

    So... have you found the answer for 2) ?
    pop000's Avatar
    pop000 Posts: 352, Reputation: 6
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    #7

    Jan 25, 2011, 06:10 AM
    Comment on Unknown008's post
    Is C
    Unknown008's Avatar
    Unknown008 Posts: 8,076, Reputation: 723
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    #8

    Jan 25, 2011, 06:16 AM

    Oh right. I didn't notice that in DrBob's answer :o
    pop000's Avatar
    pop000 Posts: 352, Reputation: 6
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    #9

    Jan 25, 2011, 07:37 AM
    Comment on Unknown008's post
    Lol yep :)
    liraz1906's Avatar
    liraz1906 Posts: 2, Reputation: 1
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    #10

    Jan 27, 2011, 08:44 AM
    Comment on DrBob1's post
    I didn't understand the different between A and C, both of them have an asymmetric carbon and have opticaly activity, is it correct?
    Unknown008's Avatar
    Unknown008 Posts: 8,076, Reputation: 723
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    #11

    Jan 27, 2011, 09:47 AM

    No, A has no chiral carbon atoms.

    The first carbon atom has 2 H atoms attached to it, so, it's already not a candidate for optical activity.
    Second carbon has a double bond, so no.
    Third carbon too has a double bond, again no.
    Last carbon has 3 H atoms bonded, so no again.
    liraz1906's Avatar
    liraz1906 Posts: 2, Reputation: 1
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    #12

    Jan 28, 2011, 08:23 AM
    Comment on Unknown008's post
    Thank you so much! Now it's clear.
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