filter Weigh the receiving flask and oil, and calculate the mass of oil you prep

Question

filter Weigh the receiving flask and oil, and calculate the mass of oil you prepared. weigh the label paper and dried salicylic acid. Calculate the mass of recovered salicylic acid, and clearly all mass measurements. Prelab Assignments: (on time: 1 p) 1. 2. Reaction mechanism as described in the second background paragraph. (3 pts) 3. rite the balanced net reaction equation for the formation of methyl salicylate at the top of a lab notebook page. Under each reaction species (not Hzso as it is a catalyst and should be written over the reaction arrow) list the mass of each compound, FM mol) (formula mass), mmol, and reacting equivalents, setting the limiting reagent as i equivalent. Equivalents are used to show the explicit mole ratio between reactants (and/or product). Simply divide all known mole amounts by the same number, the smallest one, to fill in the equivalents row. Fill in all the bold categories listed above under each product for the theoretical yield by assuming the entire amount of limiting reactant forms product. (4 pts) 4. Find the percent yield if5.80 g of product are formed. p) Theoretical yield is the maximum mass of product that can be formed from the limiting reagent. yield-actual yield 100%theoretical yield Postlab: 1) a) Recalculate a theoretical yield of oil based upon the amount of salicylic acid that was consumed (subtract the recovered mass of salicylic acid from the starting mass that you first placed in the reaction, and then rework the calculations in the prelab table). b) Calculate the percent yield of crude and distilled methyl salicylate. 2) Use a nomograph, the observed distilling temperature (boiling point at reduced pressure), and the expected boiling point at 1 atm pressure to determine the pressure that was present in the distillation apparatus during the distillation. Write this P value in your notebook. 3) Attach an IR spectrum of a drop of the distilled oil to confirm its identity.

Explanation / Answer

Prelab

1. To prepare methyl salicylate starting with salicylic acid, methanol in acid medium

2. Mechanism is shown below

3. The reaction,

       Salicylic acid + Methanol + H2SO4 ---> Methyl salicylate + H2O + H2SO4

FW    138.12               32.04         98                 152.15

d           -                     0.792  

g        13.8                  31.56          

mol    0.1                   0.99           -                       15.2

4. theoretical yield of product = 15.2 g

percent yield = 5.80 x 100/15.2 = 38.16%

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