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anonymous

  • one year ago

Can anyone help with this question!

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  1. anonymous
    • one year ago
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    Question:

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  2. aaronq
    • one year ago
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    if dont have the formulas in your notes, just dimensional analysis to match the units

  3. anonymous
    • one year ago
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    I have the formula but not sure how to complete part C, D or F

  4. anonymous
    • one year ago
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    Would you be able to show me how to do it?

  5. aaronq
    • one year ago
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    for C) you're just diluting the initial concentration by half, so instead of 0.13 M you have 0.65 M, D) is the same thing as A) For F) find the rotation of each enantiomer separately, then subtract the rotation of one from the other (from the concentrations, you can see that the D enantiomer will cause more optical effects)

  6. aaronq
    • one year ago
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    post what you have, i'll help you get it right

  7. anonymous
    • one year ago
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  8. anonymous
    • one year ago
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    I cant check if they are right till I fill in all of the blanks

  9. aaronq
    • one year ago
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    is the volume in the cuvette 10 mL?

  10. aaronq
    • one year ago
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    cuz i know the path length is 1 dm = 10 cm

  11. sweetburger
    • one year ago
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    If you don't mind me asking what level of chemistry is this?

  12. anonymous
    • one year ago
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    First semester of organic chemistry

  13. anonymous
    • one year ago
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    I think the volume is about 2 ml for a cuvette.

  14. aaronq
    • one year ago
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    is that the volume you're using to solve these?

  15. anonymous
    • one year ago
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    I was just converting from M and moles to liters. M= mol/L

  16. anonymous
    • one year ago
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    Once I found liters, I plugged the numbers into the equation. Thats how I did the first part.

  17. anonymous
    • one year ago
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    This is what I did: 119/0.130

  18. anonymous
    • one year ago
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    Moles over M

  19. aaronq
    • one year ago
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    oh right lol so then you just multiplied by the 0.16 degrees? so i think without doing any calculations, for C) is half of the initial rotation, 0.16/2= 0.08 degrees (because half of the amount) for D) it would be half of what you got in A)

  20. anonymous
    • one year ago
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    How do you do part F?

  21. cuanchi
    • one year ago
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    I think the point A) specific rotation = observed rotation / (c*l) l = cell path length in decimeters. (1 decimeter = 1 dm = 10 cm. A standard polarimeter tube is 1.00 dm in length.) c = concentration in g ml-1 for a pure liquid compound (i.e., the liquid's density), or g 100 ml-1 for a solution. specific rotation = 0.16 deg / c 1 c= 0.130 mol x (119 g/ mol) /1000 mL =0.01547 g/mL specific rotation = 0.16 deg /(0.01547 g/mL x 1 dm) = 10.34 deg mL/g dm B) is correct C) @aaronq said is going to be 1/2 of 0.16 = 0.08 D) I think that the specific rotation of a solution is independent of the concentration and is a intensive property of the solution dependent of the nature of the solute and the solvent. Then I think will be the same that A. The observed rotation is dependent of the concentration. E) the specific rotation will have the same numeric value but different sign that A because is the other enantiomer F) the observed rotation you have to subtract 0.01 moleD - 0.005 mol L = 0.005 mol D x 119 g/mol = 0.595 g this is in 100ml observed rotation = specific rotation x concentration x 1 dm observed rotation = 10.34 deg mL/g dm x (0.595 g/100mL mol) observed rotation = 0.06 deg

  22. cuanchi
    • one year ago
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    http://www.chem.ucla.edu/harding/tutorials/stereochem/calcs.html

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