. Let’s say you did this experiment again and got to the drying /filtering out the drying agent step. For each of the situations below, explain what is wrong and how would you modify this step so that it works properly. (a) You could see a water layer on the bottom of your round-bottom flask that is supposed to be for the organic layer. (b) You filtered your dried organic layer into a freshly washed (with water) round-bottom flask.

. Let’s say you did this experiment again and got to the drying /filtering out the drying agent step. For each of the situations below, explain what is wrong and how would you modify this step so that it works properly. (a) You could see a water layer on the bottom of your round-bottom flask that is supposed to be for the organic layer. (b) You filtered your dried organic layer into a freshly washed (with water) round-bottom flask.

EBK A SMALL SCALE APPROACH TO ORGANIC L

4th Edition

ISBN:9781305446021

Author:Lampman

Publisher:Lampman

Chapter80: Crystallization: Purification Of Solids

Section: Chapter Questions

Problem 4P

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1.Each of the student statements below is wrong. You will need to explain why they are not correct. (a) All my compound dissolved right away in the small amount of solvent I added at room temperature, and I didn’t need to heat it at all. This means I’m going to get lots of pure compound out. (b) I did a recrystallization of naphthalene and my percent recovery was very high (99%), so I must have pure product. (c) When you’ve dissolved all your compound in hot solvent, and you’re in a hurry, it’s ok to just place it straight into the ice bath.
Here is the procedure: Charge a 35 mL microwave reaction vessel with 12 mL of your vegetable oil and 3 mL of methanol (methanol to vegetable oil approximately at a molar ratio of (6 : 1)). Add 0.12 grams of KOH to the mixture. Heat the solution to 85 °C for 5 minutes with stirring. (Note about microwave accelerated synthesis: The reaction is traditionally performed at 65 °C for 30 minutes under reflux in a vessel open to the atmosphere. Question: Explain the rate acceleration observed in the microwave experiment.
A student rushed through this experiment. Describe the effect that the following procedural changes would have on the percent recovery of acetanilide. Briefly explain the basis of each answer.(a) Rather than adding 0.5-mL portions of boiling solvent to the acetanilide, the student added 5-mL portions of boiling solvent.(b) The student did not pre-heat the gravity filtration apparatus.(c) The student forgot to cool 5 mL of solvent in Part 5 and washed the crystals with room-temperature solvent.
3. Below are two other organic dyes that both produce a yellow color when dissolved. Which of the solvents (water, ethyl acetate, ethanol, dichloromethane, HC1) (select one solvent for each dye (dyes include disperse red 13 and methylene blue) could be used to dissolve samples of each of the dyes (individual samples, not a mixture)? HN- Radiant Yellow =1 долод Alizarine Yellow OH Na
Each of the student statements below is wrong. Explain why they are not correct. (a) All my compound dissolved right away in the small amount of solvent I added at room temperature, and I didn’t need to heat it at all. This means I’m going to get lots of pure compound out. (b) I did a recrystallization of naphthalene and my percent recovery was very high (99%), so I must have pure product. (c) When you’ve dissolved all your compound in hot solvent, and you’re in a hurry, it’s ok to just place it straight into the ice bath.
Stoichiometry: Prolonged exposure of some functionalities to the eluent (methanol) in this experiment may lead to undesirable reactions. In one case, Acetylsalicylic acid (Aspirin) can react with methanol to form salicylic acid and methyl acetate. If 800 mg of Acetylsalicylic acid and 1 mL of Methanol undergoes such a side reaction (known as "Methanolysis") to completion: (a) write a balanced equation (draw all molecules instead of writing chemical formulas), (b) what is the limiting reagent? (c) predict the grams of salicylic acid and methyl acetate to be produced in this process. Show calculations. Hint: you can determine the grams of 1 mL of Methanol through its density.
PREPARATION OF n-PROPYL PROPANOATE Q1) How can you tell, by looking at the refluxing set-up, that the reaction between n-propanol and propionic acid is over? Q2) When assembling the distillation set-up, why is it important to place the tip of the thermometer at the same height as the exit to the side arm of the round-bottom flask?
While performing a crystallization, you obtain a light tan solution after dissolving your crude product in hot solvent. A decolorizing step is determined to be unnecessary, and there are no solid impurities present. Should you perform a filtration to remove impurities before allowing the solution to cool? Why or why not?
4. Often we will ask that you scale your procedure up or down, meaning we will change the amounts of material we will use. The following is a procedure as written in an organic lab experiment. Write the procedure out as if you were asked to scale up by a factor of 2. Make any necessary changes to equipment sizes, reaction times, etc. Remember that you should never heat a reaction vessel that is more than ½ full. "In a 50 mL round-bottom flask place 2 grams of compound X and 15 mL of benzene. Reflux the reaction for 30 minutes. After the reaction has cooled, add 10 mL of ice-cold water. Collect the product by vacuum filtration and wash it with two 10 mL portions of ice-cold water."
10) What is the purpose of a brine wash (saturated sodium chloride solution) in a liquid/liquid extraction? a) Sodium chloride is alkaline and, therefore, is a good way to neutralize acidic species such as HCl or H2SO4. b) Washing with brine is convenient way to remove residual water from the organic layer prior to treating the organic layer with a solid drying agent. Sodium chloride is an organic soluble material which provides a "seed" which c) encourages crystal growth. d) Sodium chloride aids in dissolving materials that are typically insoluble in both organic and aqueous media.
You place 2.00 mL of bromobenzene in an addition funnel containing 8.0 mL diethyl ether (the total volume of the solution is 10.0 mL). You slowly add the bromobenzene solution into a flame-dried flask containing excess magnesium metal. You are making a Grignard reagent. Assuming that all of your bromobenzene is converted to the Grignard reagent and that you did not lose any diethyl ether solvent, what will be the molarity of the Grignard reagent that you produce? You are assuming the total volume of the solution remains 10.0 mL.
4. In a distillation of a mixture of acetone (bp. 56°C and dichloromethane bp. 40°C), a fraction averaging 48°C was collected that never exhibited a plateau temperature. Show using temperature as an indicator of purity what the % of acetone is in this fraction. (Hint: this is similar to the question of refractive index in the last assignment) Please answer very soon will give rating surely