answer

watching

views

11 Dec 2019

In the lab: extraction, purification and analysis of turmeric natural products, Calculate the amount of 3M HCI that would be needed to neutralize the 35 mL of 1M NaOH used in the extractions when you add 20mL 1M NaOH and 10mL saturated sodium chloride to a seperatory funnel which contains 5mL turmeric (extracted from MTBE) and 5 mL of MTBE, shake it, seperating the layers.. You then drain the lower aqueous layer into a flask and leave the top (MTBE) layer in the seperatory funnel and extract it a second time with 15 mL 1M NaOH then combine the NaOH layer with the previous layer in a flask and save for later..

answer

watching

140

views

For unlimited access to Homework Help, a Homework+ subscription is required.

You have 0 free answers left.
Get unlimited access to 3.8 million step-by-step answers.

Get unlimited access

Already have an account? Log in

Nestor RutherfordLv2

13 Dec 2019

Unlock all answers

Get 1 free homework help answer.

Already have an account? Log in

Join us on Discord

Chemistry Study Group

Join now

Related questions

Experiment: Extraction to seperate benzoic acid and naphthalene.

Procedure-

Place 2 g of a 1:1 (by weight) mixture of benzoic acid and naphthalene in a small beaker; record the exact mass of the mixture in your notebook. Add 35 mL of dichloromethane to the beaker and stir until the solid mixture has completely dissolved. Carefully pour the solution into a separatory funnel.

Add 20 mL of 3.0 M NaOH to the separatory funnel, stopper it, and shake the mixture with frequent venting. When the layers have separated, drain the bottom portion into a clean flask. Pour the aqueous layer into another clean flask labeled âaqueous layer.â Pour the organic layer back into the separatory funnel and extract with a second portion of 3.0 M NaOH. Drain the bottom layer into a clean flask labeled âorganic layerâ and pour the aqueous layer into the âaqueous layerâ flask.

Put the organic layer back into the separatory funnel and shake with 20 mL of saturated NaCl solution. Drain the organic layer into a clean, dry flask and add a small amount of anhydrous calcium chloride to dry the solution. Allow this solution to stand for at least ten minutes, with occasional swirling, then remove the drying agent by gravity filtration; place the filtrate in a round-bottom flask and remove the solvent by simple distillation or by using the rotovap. Once the dichloromethane has been removed, scrape the crystals out of the round-bottom flask into a clean, labeled, tared vial, and determine the weight and melting point of the naphthalene crystals.

Acidify the combined aqueous layers with 6.0 M HCl until the solution tests acidic to litmus paper. A white precipitate of benzoic acid should develop as the solution is neutralized. Chill the solution in an ice bath for at least ten minutes to finish precipitating the solids, then collect the benzoic acid by vacuum filtration. Wash the crystals with a small amount of cold water; then scrape the crystals into a clean, labeled, tared vial and allow to dry. Once the crystals are dry, determine their weight and melting point.

Post-Lab Question:

Write a balanced equation (using structures) for the reaction that takes place when the aqueous layer is acidified with HCl. Why does the precipitate form when the solution is neutralized? (HINT: benzoic acid (slightly soluble in water) and sodium benzoate (soluble in water)

Please consider the preperation of benzoic acid: a Grignard Reaction.

Bromobenzene and diethyl ether is used in the formation of Grignard reagent. Note: procedure is listed below for reference

QUESTION:

Procedure:

* add 1.2g of magnesium and 3 crystals of iodine to RB flask and immediately assemble the dry water condenser and drying tube containing cotton and anhydrous calcium chloride to RB flask

*then add 5.2 mL bromobenzene to 5 mL of diethyl ether to seperatory funnel and turn on condenser

* add about one third of ether-bromobenzene mixture down the condenser into the RB flask by momentarily removing drying tube. Place the drying tube back as quickly as possible.

* now add 30 mL of ether to the bromobenzene-ether mixture remaining in the seperatory funnel

*to initiate reaciton, place hands under flask and gently swril

* once the reaction maintains reflux, remove hands and set the flask down on a cork ring

*maintain the vigorousness of the reaciton by continuously adding 3.5 mL portions of diluted bromobenzene-ether mixture every 30 seconds

* make sure all of the bromobenzene-ether mixture has been added

* now obtain some dry ice, CO₂ (s) and transfer 50 mL of this to the reaciton mixture inside the flask

*when all the dry ice has been added, add 80 mL of 6M HCl (aq) to flask

* finally, add 100mL of solvent grade diethyl ether (not anhydrous) and carefully stir

* transfer mixture to a 250mL seperatory funnel, allow layers to seperate and discard the lower aqueous layer

*now add 20 mL of 6 M NaOH (aq) and add 100mL of deionized water to seperatory funnel containing the ether solution

* drain the lower aqueous layer into a large beaker and slowly acidify using concentrated 12M HCl (aq). Stir the mixture and add HCl (aq) until pH is about 1-2 pH units.

*cool solution in ice-water bath and collect precipitate of benzoic acid

Please consider the preperation of benzoic acid: a Grignard Reaction.

Bromobenzene and diethyl ether is used in the formation of Grignard reagent.

PLEASE READ PROCEDURE TO HELP ANSWER THE QUESTION:

Procedure(question is in the pic below):