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No of C=C bond in carbonyl compound

  1. Aug 30, 2014 #1
    1. The problem statement, all variables and given/known data


    Compound X has the following composition by mass : carbon(64.3%) , 7.1% of hydrogen and oxygen (28.6%) . X reduces Fehling's solution to CuO . Copper( I) oxide .0.1 mol of X react with 4480cm3 of hydrogen gas in the presence of nickel catalyst. What 's the possible structural formula of X ?
    there are 2 choices ..
    CH2=CH-CHO
    CH3-CH=CH-CH=CH-COH

    THE ANS IS CH2=CH-CHO ...Why ? can anyone explain on this? thanks in advance!


    2. Relevant equations



    3. The attempt at a solution
    mol of hydrogen gas = 4480/22400= 0.2 mol

    if there's only one C=C bond , then 1 mol of X react with 1 mol of H2 gas ..

    But 0.1 mol of X react with 0.2 mol H2 gas , so there are 2 C=C bond in X .... my choice would be CH3-CH=CH-CH=CH-COH ...
    but the correct ans is CH2=CH-CHO
     
  2. jcsd
  3. Aug 30, 2014 #2

    Borek

    User Avatar

    Staff: Mentor

    No idea about everything else, but of the two compounds given only one fits.
     
  4. Aug 31, 2014 #3
    so which one is correct?
     
  5. Aug 31, 2014 #4

    Borek

    User Avatar

    Staff: Mentor

    Have you tried to find the experimental formula from the numbers given? Or even simpler - have you tried to find the percent elemental compositions from the given formulae?
     
  6. Aug 31, 2014 #5
    i got ratio of ratio of C:H:O = 3:4:1
    using precentage
     
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