Background
Use of a separatory funnel
A separatory funnel is a standard piece of equipment used in synthetic chemistry labs.  Generally made of glass, the funnel has a conical body, a glass or Teflon stopcock to control the release of solution from the bottom of the funnel and a glass or Teflon stopper at the top.
The stopper has to be removed in order to release the liquid from the funnel. If the stopper is not removed, the vacuum that forms above the liquid will prevent the solution from draining properly. Eventually, the vacuum will suck air in (from the stem), the bubbles that form will cause the phases to mix again, defeating the purpose of the separation.

Because seals are very important to keeping the liquid in the funnel, glass stoppers and stopcocks should be greased to produce a good seal. Teflon joints should not be greased.
Performing an extraction
a. Place the separatory funnel in a support. Remove the stopper and make sure that the stopcock is closed.
b. Add the solution to be extracted. The funnel should not be filled more than half-full. Add the extraction solution and place the stopper on top. There should still be some room afterwards.

c. Take the separatory funnel out of the support and hold it tightly at the stopper and the stopcock. Invert it slowly and vent (open the stopcock) away from yourself and others. You will hear a kind of whoosh when the pressure is released.
d. Close the stopcock and shake the funnel gently. Vent it again. Repeat this step until no more gas escapes.
e. Place the separatory funnel back into its support. Allow the layers to separate. Then remove the stopper and drain the bottom layer into a clean container. At this point, you need to know which layer contains your desired product. The layers separate due to immiscibility and density.  The less dense liquid will reside in the top layer. As organic liquids are generally less dense than water, aqueous solutions will generally form the bottom layer in a separation.
Patented process
In the 1980’s a patent was developed that separated ethanol from water by separatory funnel, rather than by distillation.  It involves the use of several chemical reactions and techniques that cannot be recreated exactly in the chemistry teaching lab, but the basic concepts of the patent can be demonstrated by separating a mixture of water and ethanol.  At first the ethanol will be homogenous with the water and mix well, but upon addition of an organic solvent that binds ethanol, it will separate as the upper layer and can be collected.  When optimized, a process like this could have profitable use in beer, wine or alcohol or even pure ethanol industries.  Until that optimization is completed however, the inability to complete the patented process in its entirety leads to a less than 100% efficiency of separation.
Separation of immiscible liquids is a concept that requires the understanding of homogenous and inhomogeneous solutions, so these concepts are incorporated into this experiment.  Since ethanol is miscible in water before addition of diethyl ether and sodium acetate, it can be seen during the experiment that a molecular interaction is occurring that causes the ethanol to separate. 
Volume %, mass % and proof (ethanol)
Concentration is important in all of chemical and physical understanding.  Knowledge of volume % and mass % will always be necessary when gathering and analyzing quantitative data, especially for liquids.  The distinction of volume % (being dependent of temperature and pressure) and mass % (independent of temperature and pressure) is made and exemplified in the experiment.  The meaning of “proof” (when referring to ethanol in water) can be demonstrated and, in normal daily life, has usefulness if one is consuming alcoholic beverages.
The concept of concentration is very wide and diverse, while still remaining one of the most useful and common tools in the chemist’s box of skills.  Considering a pure material and an impurity; when only the pure material exists, its concentration is maximized and addition of the impurity leads to a change in concentration as the system gets bigger.  With continued addition of the impurity, the concentrations will continue to change respectively for each material.  Most of the time, the concentration of one species is considered at one time, such as molarity, volume % and mass %, where the quantity of species for consideration is the numerator and the quantity of total system is the denominator for the fractional ratio.
Molarity:         M = moles of species for consideration/total Liters of solution
Volume %:      volume of species for consideration/total volume (same units for numerator and denominator)
Mass %:           mass of species for consideration/total mass (same units for numerator and denominator)
Although volume % is widely used, the actual quantities can depend on the temperature and pressure of the species in the system, so volume % can vary.  Mass % on the other hand, does not change with temperature and pressure. 
For example, in the species Mg(BH4)2 the mass % of Mg would be: 
mass%(Mg) = mass of Mg/mass of Mg(BH4)2 = 24.31g/54.01g = 0.45 ~ 45%. 
The definition and use of terms such as solute, solvent, solution, homogenous and inhomogenous have importance when considering concentration.
In the USA and many other places in the world, when considering an alcoholic beverage, usually the concentration of pure alcohol in the drink is the proof.  The proof of a drink is exactly equal to twice the volume %, so pure ethanol would have a theoretical proof of 200, which is why Bacardi 151 packs so much punch.  The proof of beer and wine are low, usually around 10-12 and 24-29, respectively, so volume percent is used more than the term proof (Most beer is about 5% ethanol, wine is about 12-15%). 
The alcohol content of beer is usually expressed as volume percent of ethanol (ABV, or alcohol by volume). This concentration unit refers to the volume of ethanol present in a given volume of solution. For example, one liter of a 20% by volume ethanol solution would be formed by mixing 200 mL of ethanol with enough water to make the final volume one liter. It does not follow, though, that a 20% by volume solution of ethanol contains 80% by volume of water. When these liquids are mixed the volumes are not additive. From the top graph at the right, one can see that 815 mL of water must be added to 200 mL of ethanol to bring the volume to one liter.

Interconverting concentration units from volume to mass involves a knowledge of density of either the solute, the solution, or both. Molarity as a concentration unit refers to a volume of solution, so one need only know the density of the solute, ethanol, to convert volume percent to molarity. First convert the volume of ethanol in one liter (10 times its ABV) to its mass (assuming a density of 0.789 g/mL) and divide by the molar mass to get the number of moles in one liter.
It is worthy to note at this point that the solutions used in this lab are combinations of 95% ethanol and water.  Ingestion of ethanol at that concentration is capable of doing damage to human mouths, throats and internal organs, accidental ingestion could be cause for emergency medical attention, so appropriate measures should be taken when handling the solutions to avoid inhalation, skin contact or ingestion.  Equally harmful diethly ether and sodium acetate that are necessary for separation require the same care when handling.  Appropriate measures should be taken when handling the solutions to avoid inhalation, skin contact or ingestion.
 Efficiency of separation
In the first semester of general chemistry we normally make calculations and predictions of reactions based on the premise that the reaction or process taking place proceeds to 100% completion.  The reality in most reactions is that some of the process falls short of completion.  The degree to which a reaction or process proceeds is its “efficiency”.  As mentioned in the section regarding the patented process used as the basis of this experiment, the inability to completely recreate the process’s more complex steps has lead to a lower than 100% efficiency.  As a result of many trials of the process below it was determined that the efficiency of the process is 81.0%. This value can be used to modify any results you may collect to determine the actual concentration of the unknown solution.