Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Saturated Fatty Acids

  1. Sep 25, 2006 #1
    I got my test back and one of the questions was the following

    Which is a property of a saturated fatty acid?
    (a) no double bonds
    (b) (c) rubbish
    (d) maximum number of single bonds

    I answered (d), but the professor says it's (a).

    I don't think it's (a) for two reasons-- a pi double bond between carbon and oxygen in the carboxyl group of hte molecule (as 'a' never specified no double bonds in carbon to carbon chain), and (d) is correct--apart from the pi carbon/oxygen bond, all others must be single in order for the fatty acid to be fully saturated with hydrogen.

    Where am I going wrong?
  2. jcsd
  3. Sep 25, 2006 #2
    10+ views and nobody has even an opinion?
    I sincerely think I might be right, can anybody confirm it?
  4. Sep 25, 2006 #3


    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    It's a lousy question; he offered lousy answers. That said, go with "a." You can expoxidize a double bond and get a "maximum number of single bonds," gonna be a rather weird acid, but semantically not a "saturated fatty acid." Probably best not to argue from your "semantic" point that the acid contains a carbonyl group --- if you can "sell" the ambiguity of the two choices in a diplomatic fashion, you might stand a chance. If you're dealing with a "hard-head," give it up for this case, and remember it for the next.
    Last edited: Sep 25, 2006
  5. Sep 25, 2006 #4
    First, thanks for the reply =D

    I agree it was a lousy question (the truth being my professor does not seem truly sure of what he is doing at times). However, I fail to see how "a" could be a better answer than "d" when I have to make assumptions in order for "a" to be correct.

    He is a hardhead and was rather rude when I asked him about it... he told me I should've known to ignore the carboxyl group. But if we ignore the carboxyl group, what do we call the molecule? Fatty? =P And how would it bond to glycerol? In fact, how would that make "d" wrong?

    Luckily if I opt to challenge (which I'm thinking about), soembody else will review the challenge.

    Btw, I have no clue what expoxidize means, but it sounds complicated and I wouldnt' expect us to have to know it.
  6. Sep 25, 2006 #5


    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    Any challenge needs to be based on the ambiguities implicit in both possible answers, and on the fact that you have to make assumptions in both cases. Do NOT try to assert that you are correct and the instructor is NOT --- that will create bad feelings. Leave room for the "face-saving" acknowledgment that the answers were ambiguous.
  7. Sep 25, 2006 #6
    I think you may win if you restate the question as a true-false type question in appeal. Thus the question "does saturated fatty acid have double bonds--true or false--and the correct answer is false due to C = O bond. Next the question "does saturated fatty acid have maximum number of single bonds" -- true or false--and the correct answer is true.
    Thus, while answer (a) can be false is some situation answer (d) can never be false--thus answer (d) is "better" answer than (a). Good luck with your appeal.
  8. Sep 26, 2006 #7
    I'm goign with that strategy, but I always try to be as polite as possible (although in a class of 100s in highly unlikely for him to remember who I am, however I like to believe I'm a good mannered individual anyway, go figure =/)
  9. Sep 26, 2006 #8
    end3r7--there is an error in my first true-false question, you need to add the word "no" before the words "double bonds"--this is the way the test question (a) is stated. Sorry for the confusion, good luck with your appeal.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook