PHARCAL LAB - Laboratory Module 12: Extraction

Transfer of a solute from one solvent to another is called ________________.

extraction

The__________________ forms the basis of extraction as a method of separation. The law concerns the quantitative partitioning of a substance between two immiscible solvents at a given temperature. It states that the substance will distribute or divide itself between the two solvents so that the ratio of the concentration  in one solvent to the concentration in the second solvent is constant.

Nernst Distribution (Partition) Law

_________________ (in their molecular or undissociated form) tend to partition towards organic solvents because they are more soluble in them than in water. Thus, these may be extracted from the aqueous solutions

Organic compounds

If __________ are added to water, the water solubility of the organic substance may be depressed still further, and the process of extraction will be facilitated.

electrolytes

The reduced solubility of the organic compound in water in the presence of electrolytes is referred to as “__________________________.” This phenomenon is a result of the attraction of the salt ions for the water molecules which leads to a reduction of the aqueous environment adjacent to the organic molecules.

salting-out effect

Extraction of these tissues with a water-immiscible solvent is useful for ____________________. Often _____ is used for this purpose.

isolation of the natural products
ether

In a simple extraction method, the compound is __________  in one of the two immiscible or slightly miscible solvents and then _________ with the other. In order to efficiently extract a solute from a solution, it is always better to use _________________ of the second solvent than to use a single extraction with a large portion.

dissolved
shaken
several small portions

the solvents are allowed to separate into two layers with the _________ liquid on top. The immiscible liquids are separated with the aid of a __________ funnel.

lighter
separatory

The ______________ is the piece of apparatus used in extraction procedure.

separatory funnel

To fill the separatory funnel one usually supports it in an ________ attached to a ___________.

iron ring
ring stand

Since it is easy to break a separatory funnel by “clanking” it against the metal ring, it is recommended that three short lengths (about 3 cm each) of rubber tubing be __________________  along their length.

cut and split open

An _____________ is placed in the top opening, and both the solution and the extraction solvent are poured into the funnel.

ordinary funnel

The separatory funnel is swirled gently by holding it by its upper neck, and then it is stoppered. The separatory funnel is picked up with two hands and held horizontally with one hand holding the stopper and the other holding the neck along the stopcock. The separatory funnel is then carefully shaken in a ________ motion.

figure 8

It is essential to hold the stopper in place _________ because the two immiscible solvents build up pressure when they mix, and this pressure may force the stopper out of the separator funnel

firmly

The pressure results from the two partial vapor pressures of the solvents adding together on mixing; the vapors of both solvents are now in equilibrium. To release this build-up of pressure, the funnel is vented by holding it _________  (holding the stopper securely) and _______opening the stopcock.

upside-down
slowly

Shaking and frequent venting should be continued until the “whoosh” is ___________________

no longer audible

Approximately ______ of the lower layer is allowed to drain before the stopcock is closed

3/4

The remaining upper layer is removed by pouring it from the ____________ of the separatory funnel.

top opening

To minimize contamination of the two layers, the lower layer should always be removed from the _________ of the separatory funnel and the upper layer from the ________ of the funnel.

bottom
top

After an organic solvent has been shaken with an aqueous solution, it will be “____,” that is, it will have dissolved some water even though its miscibility with water is not great.

wet

To remove water from the organic layer, a ___________ is used.

drying agent

A _____________ an anhydrous inorganic salt which acquires waters of hydration when exposed to moist air or a wet solution.

drying agent

If a solution is WET, the drying agent usually will ____________ and stick to the flask.

clump together

If the solution is DRY, the drying agent will shift or ___________ on the bottom of the flask.

move freely

A wet solution usually will appear __________ ; a dry one will be _________.

cloudy
clear

________________ is the best all-around drying agent. It is mild and effective, but it will not free a solution completely of water. . It must also be used at room temperature to be effective; it cannot be used with boiling solvents.

Sodium sulfate

The __________ salts must be used.

Anhydrous

What are the materials used in this experiment?

1. -

2. -

3. -

4. -

5. -

Benzoic acid
Sodium chloride
Sodium sulfate
Ethyl acetate
Vegetable oil

What are the 2 main stages in this procedure?

1. -

2. -

Extraction
Drying of liquids

________________ is an irritant to the skin, eyes, nose, and throat, and an asphyxiant at high vapor levels. Wear appropriate personal protective equipment, such as safety goggles, gloves, masks, and laboratory gown at all times.

Ethyl acetate

DO NOT HEAT ___________, such as chloroform, dichloromethane, carbon tetrachloride, diethyl and petroleum ether, acetone, ethyl acetate and alcohols among others, over a DIRECT FLAME OR HOT PLATE

organic solvents

Place the crystals in a _____________ and dispose in the _____________.

scratch paper
solid wastes bin

Withdraw the AQUEOUS layer into a 100-mL __________

Pour the UPPER OILY LAYER into a separate 100-mL ________________

beaker
Erlenmeyer flask