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Theoretical Yield and Percentage Yield of Organic Molecules

  1. Oct 29, 2014 #1
    1. The problem statement, all variables and given/known data

    1. A student investigated several esters, and made octyl acetate, an ester with the fragrance of oranges. The student used the acid derivative, acetyl chloride (as you saw decanedioyl dichloride used to make 6,10 nylon) and 1-octanol. Using the following information, calculate the theoretical yield for the student. (Hint: you need to calculate the molar masses and to identify the limiting reagent).

    Structural Equation
    tcc6aZC.png

    Quantities used:

    acetyl chloride: 0.654 g

    1-octanol: 1.401 g.

    Calculate theoretical yield. Enter your answer with three significant figures in grams.

    2.
    A student began the aspirin synthesis with 2.083 g salicylic acid and excess acetic anhydride. The student's actual weighed yield was 2.534 g. Calculate the % yield. Give your answer as % with 3 significant figures (that is 1 decimal place in your %age). Do not include % symbol.

    UuJb1st.png
    2. Relevant equations

    Percentage Yield = Actual yield/theoretical yield

    3. The attempt at a solution
    1. I figured out the equation: C8H18O + CH3COCl ----> C10H20O2 + HCL (1:1 Ratio)
    Figuring out the moles for 1-octanol and acetyl chloride gives me acetyl chloride as the limiting reagent with 0.00833moles. Multiplying this with the molar mass of octyl acetate gives me 1.44g. Is this right?

    2. Once again we have a 1:1 ratio. We are given that salicylic acid is the limiting reagent. 2.083/138.13 = 0.0150 moles theoretically of aspirin. 0.0150mol x molar mass aspirin (180.17g/mol) = 2.7169g.
    2.534/2.7169 = 93.3%.
    Thanks for the help, I think my answers are right but I normally get something simple wrong.
     
    Last edited: Oct 29, 2014
  2. jcsd
  3. Oct 29, 2014 #2

    Borek

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    Staff: Mentor

    Your images don't show for us.

    Yes, acetyl chloride is a limiting reagent, yes 1.44 g of octyl acetate looks OK.
     
  4. Oct 29, 2014 #3
    Sorry about that, think I fixed it now
     
  5. Oct 29, 2014 #4

    Borek

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    Staff: Mentor

    Second image has nothing to do with the reaction from the question.
     
  6. Oct 29, 2014 #5
    That's embarrassing! Sorry about that.
     
  7. Oct 29, 2014 #6

    Borek

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    Staff: Mentor

    Other than that logic looks good.
     
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