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Stoichiometry, Part II (and Percentage Yield)

  1. Oct 3, 2005 #1
    Please (pretty please) check all of my work!

    1) In an oxidation reaction, ethanol (C2H5OH) is converted to a ethanoic acid (C2H4O2) with a percentage yield of 70%. If you start the reaction with 360g of ethanol, how many grams of ethanoic acid would you expect to produce?
    Stoichiometry is 1:1 between the compounds.

    % yield = (actual value/expected value) *100

    Given: % yield = 70

    Find: expected value C2H4O2 in g

    Actual value C2H4O2 in g:
    360 g C2H5OH (1 mol C2H5OH / 46.068 g C2H5OH) (1 mol C2H4O2 / 1 mol C2H5OH) = 7.81454 mol C2H4O2

    7.81454 mol C2H4O2 (60.052 g C2H4O2 / 1 mol C2H4O2) = 469.2785 g C2H4O2 = actual value ??

    70 = (469.2785/expected) * 100
    expected = 469.2785/.70 = 670 g C2H4O2 ??

    Did I muddle this problem big time? I'm confused with what is the actual value and what is the expected (theoretical?) value. Did I confuse the actual for the expected?? Do you use 70% at all?


    2) In an oxidation reaction, ethanol (C2H5OH) is converted to a ethanoic acid (C2H4O2). In an Experiment, a chemist starts with 149.00g of ethanol and forms 180.00g of ethanoic acid. What is the percentage yield of the reaction? Stoichiometry of the reaction is 1:1 for the mentioned compounds.


    % yield = (actual value/expected value) *100

    Given: 180.00 g C2H4O2 = actual value g C2H4O2 ?

    Expected value of C2H4O2 :
    149.00 g C2H5OH (1 mol C2H5OH / 46.068 g C2H5OH) (1 mol C2H4O2 / 1 mol C2H5OH) (60.052 g C2H4O2 / 1 mol C2H4O2) = 194.2291 g C2H4O2 ??

    180 g / 194.2291 g C2H4O2 *(100) = 92.674 % ??

    Gosh, I hope I didn't confuse my values or molar masses again!

    Thank you. I am desperate for help. :cry:
     
  2. jcsd
  3. Oct 4, 2005 #2
    Anyone at all? Please? (Are my calculations correct?)

    Thanks.
     
  4. Oct 4, 2005 #3
    Please confirm if I did something correctly.

    Thanks for your patience.
     
  5. Oct 12, 2005 #4
    Your calculations look correct to me.:smile:
     
  6. Oct 13, 2005 #5

    GCT

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    Science Advisor
    Homework Helper

    what you calculated here is the theoretical yield, now how is your theoretical yield less then you're actual percent yield? Think about it.

    2) seems fine
     
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