After the liquid-liquid extraction of caffeine, you are removing the dichloromethane solvent on the rotary evaporator. After 30 mins the solvent volume has not decreased. This may be because: a. You have the aqueous layer on the rotary evaporator and are trying to remove water, instead of the organic layer b. You picked up the wrong solvent bottle, and this isn’t dichloromethane c. It typically takes 30 mins to remove the low-boiling dichloromethane solvent on a rotary evaporator d. You forget to close the vent on the rotary evaporator e. Either a), b), or d).

After the liquid-liquid extraction of caffeine, you are removing the dichloromethane solvent on the rotary evaporator. After 30 mins the solvent volume has not decreased. This may be because: a. You have the aqueous layer on the rotary evaporator and are trying to remove water, instead of the organic layer b. You picked up the wrong solvent bottle, and this isn’t dichloromethane c. It typically takes 30 mins to remove the low-boiling dichloromethane solvent on a rotary evaporator d. You forget to close the vent on the rotary evaporator e. Either a), b), or d).

EBK A SMALL SCALE APPROACH TO ORGANIC L

4th Edition

ISBN:9781305446021

Author:Lampman

Publisher:Lampman

Chapter88: Column Chromatography

Section: Chapter Questions

Problem 5P

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Which statement about liquid-liquid extraction is not correct? * A- A solvent must be available that is miscible with the solution containing the substance to be extracted. B- The solvent used for extraction must have a good ability to dissolve the desired substance. C- The denser solution forms the bottom layer in the extraction funnel. D- The extraction funnel must be vented during the extraction procedure to prevent excessive build-up of pressure inside the extraction funnel. E- All these statements are correct.
Extraction of Caffeine Post-lab 8. Ethanol is miscible with water. (After all, alcoholic beverages don t separate into an “alcohol‟layer” and a “water layer.”) Assuming that caffeine is soluble in ethanol, could you useethanol as a solvent to extract caffeine from coffee (rather than using dichloromethane asthe extraction solvent)? Explain why or why not. 9. A 12 oz can of Coke contains 46 mg of caffeine. One fluid ounce is equivalent to 29.57 mL(1 oz = 29.57 mL). What is the concentration of caffeine in Coke, in units of mg/mL? Showyour work. 10. What is an alkaloid?
The liquid-liquid extraction is the classical technique in chemistry to isolate a target component from a mixture. Organic Solvent is the usual solvent being used along with water. TRUE or FALSE
One of the problems that can be encountered in recrystallization is the failure of the solute to crystallize. In which of the following scenarios could that happen? a. Cooling the filtrate in an ice bath. b. Using a wide bore, long-stemmed funnel in the hot filtration step. c. Addition of too much water in the receiving flask. d. Washing the residue with cold solvent
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.
Accurately weigh out about 6g copper(ii) sulfate crystals into a weighing boat. Use the copper(ii) sulfate crystals to make up 250cm3 of standardized copper (ii) sulfate solution Pipette 25cm3 of this solution into a conical flask Add 1.5g potassium iodide and swirl thoroughly Titrate this solution with standard 0.1 moldm-3 Na2S2O3 in a burette. When the iodine color fades, add 1 cm3 starch indicator. Use your titration data below to calculate the percentage by mass of copper in the copper(ii) sulfate crystals.
Pls do fast within 5 minutes and i will give like for sure Solution must be in typed form To plan a liquid–liquid extraction we need to know the solute’s distribution ratio between the two phases. One approach is to carry out the extraction on a solution that contains a known amount of solute. After the extraction, we isolate the organic phase and allow it to evaporate, leaving behind the solute. In one such experiment, 1.235 g of a solute with a molar mass of 117.3 g/mol is dissolved in 10.00 mL of water. After extracting with 5.00 mL of toluene, 0.889 g of the solute is recovered in the organic phase. If we extract 20.00 mL of an aqueous solution that contains the solute using 10.00 mL of toluene, what is the extraction efficiency?
In an extraction procedure, it is advisable to: O put the aqueous layer down the drain put the organic layer in the aqueous waste throw away all layers as soon as you have extracted them save all layers until an experiment is complete
Extraction of Caffeine Post-lab 4. What does it mean for two solvents to be immiscible? 5. On the report sheet, you calculated your percent recovery of caffeine. a. If your percent was less than 90%, give at least one reason why it was less. b. A group of students have their percent yield more than 100%, give at least one reasonwhy it was more than 100%. Do NOT simply say “human error.” Be specific about the typesof errors (human or otherwise) that may have occurred, leading to a recovery more than eorequal to 100% (Is this possible Why?) 6. Based on what you observed during this experiment, is dichloromethane denser OR lessdense than water? Explain your reasoning. 7. Based on what happened in this experiment, is caffeine more soluble in water OR moresoluble in dichloromethane? Explain your reasoning. 8. Ethanol is miscible with water. (After all, alcoholic beverages don t separate into an “alcohol‟layer” and a “water layer.”) Assuming that caffeine is soluble in ethanol, could…
You are attempting to purify a compound via recrystallization. You prepare the process through the following method: 1) Dissolve the material in a minimal amount of hot EtOH. 2) Slowly add hot water until the compound is slightly cloudy. 3) Add a small amount of EtOH until the solution is just clear (still hot). 4) Cool to RT. Upon cooling to RT you notice that the compound is not precipitating out of solution. You decide to boil off some ethanol. Upon completing this step and cooling to RT you notice that the compound is precipitating out as desired! In which solvent is your compound the least soluble? Ethanol O Water O The ethanol water mixture Insoluble in all of these solvents
A student is trying to perform a single solvent recrystallization of compound X using methanol. He observed that compound X is insoluble in methanol at room temperature and also insoluble at boiling temperature. Is methanol a good recrystallization solvent? A. Yes, you want to only dissolve the impurities and the sample should remain undissolved. B. No, you need a solvent which fully dissolves the sample only at room temperature so that it can crystallize in the ice bath. C. No, you need a solvent which dissolves the sample only at boiling temperature for selective crystallization upon cooling. D. Yes, you don't want the solvent to fully dissolve the sample at both temperatures so that it will crystallize in the cooling step. A student obtained a supersaturated solution in the recrystallization experiment. Which of the following methods should he/she perform to induce crystal growth? (Can select more than 1) A. Add a crystal of pure acetylsalicylic acid B. Place the solution in an ice…
i need help determining amount recovered in an extraction. i started with a .51g mix of naphlathene/benzoic acid. then, i ended up with the organic in the flask weighing 56g, with the initial weight of the flask without product being 46g. how do i determine amount recovered AND the % recovery?