LAb+3+Distillation+of+Acetone


 * Lab 3: Distillation**


 * Introduction:**

In organic chemistry the process of distillation can be used for purification or identification of a compound. Distillation is utilized to separate volatile and non-volatile substances from each other thereby purifying the compound. As a liquid reaches its boiling point, vapor pressure will equal that of the applied pressure. Compounds with a higher vapor pressure will boil at lower temperatures while compounds with lower vapor pressure will boil at a higher temperature resulting in purification. The more volatile liquid will vaporizes and leave behind a less volatile substance in which impurities are contained. Pure vapors are then cooled and condensed on a cold surface. From this vaporization-condensation cycle, a pure liquid is collected for identification. During experimentation, the simple distillation of acetone and comparison by infrared spectroscopy were two techniques performed for verification of a distilled pure liquid.


 * Procedure:**

The full experiment lab procedure can be found below. [|Distillation of Acetone]

Lecher, Carl S. "Simple Distillation: Purificaiton and Reuse of Acetone." //Green Chemistry at the University of Oregon//. GEMS, 2007. Web. .

1) A complete and accurate assembly of the distillation apparatus is required prior to conducting the experiment. It allows a solution to be heated to a gas phase then rapidly condensed through a water chilled surface. This water condenser is a one way closed chamber leading to the collection vessel of a round bottom flask.

2) Once the apparatus is assembled add 40.0 mL of contaminated acetone with a stir bar to be distilled. To ensure an even boil and prevent contamination of the pure vapors at boiling point, the heated flask is placed in a water bath on an elevated hot plate. Careful monitoring of vaporization is necessary to ensure impurities remain liquid in the heated vessel. The apparatus is suspended using a ring stand and clamp to allow the heat plate to be quickly removed while monitoring this process. A temperature probe is placed inside the heated flask to record the distillation process. With the hot plate set at approximately 20% power, the first data points from the temperature probe should be recorded when the first drops of the condensed solution reach the round bottom flask at the recieving end of the condensation chamber.

3) The temperature should be recorded as the solution begins to steadily collect in the smaller collection flask and verification is made that the temperature has stabilized.

4) A second verification should be made to ensure that the thermometer reading is comparable to the expected boiling range of the substance. If the temperature reading is not within this known range, then a thorough inspection of the thermometer placement should be conducted.

5) The desired rate of distillation is roughly one to three drops per second accumulating in the smaller collection flask. Distillation should continue untill the larger boiling flask contains 5mL of the initial solution or the upper end of the expected boiling range is reached. It is important to completely remove this larger boiling flask from the heating element prior to the initial substance completely boiling off.

6) The recovered acteone should be verified for purification after the distillation process. To ensure that the recovered acetone is of an acceptable purity, two techniques should be utilized. These are comparison of boiling points and infrared spectroscopy.


 * Data:**
 * Acetone**


 * Initial Mass Contaiminated Acetone: 31.140g**
 * Initial Volume Contaiminated Acetone:** 40.0mL


 * Recovered Mass Acetone: 24.360g**
 * Recovered Volume Acetone: 31.29mL**


 * Note time laps lasted about 10 minutes. The graph includes starting temperature and the last three minutes of the temperature readings the middle section of data was lost due to LabQuest technical difficulties.**

After the simple distillation apparatus was properly set up, 40.5 mL of impure acetone was measured and weighed. The acetone solution was placed in the boiling vessel with a stirring bar and a water bath was raised to begin the heating. The hot plate was set to 20% power while stirring was set to low. An initial temperature of 24.0 degrees Celsius rose slowly until the vapors reached the three-way adaptor. The temperature rose to 50.4 degrees Celsius when the first drop of liquid traveling through the condensing tube dripped into the collection beaker. Equilibrium was reached between 50.1 and 50.4 degrees Celsius with a drip rate of about three drops per second in the collection beaker. The hot plate power was reduced to 10% to attempt to slow condensing and rapid boiling. Soon after the reduction of power, the temperature climbed and spiked at 54.3 degrees. As the peak in temperature occurred, the lab jack was lowered and heat was reduced from the boiling beaker. Approximately 35 ml of the pure solution condensed in the collection beaker with pure acetone. Remaining pot residue was discarded. The percent recovery of pure acetone was calculated with the following equation. Distillation yielded a 78.227% percent recovery. The pure acetone was then compared to the impure acetone by infrared spectroscopy for purity analysis.
 * Graph 1: Acetone Distillation Temperature Reading.**
 * Readings taken two minutes prior to completion of distillation.**


 * Graph 2: Infrared Spectroscopy Readings**
 * Graph contains readings on recovered Acetone and initial contaminated Acetone.**


 * Analysis/Discussion:**

During experimentation, the distillation range of temperatures at equilibrium fell between 54.1-54.3 degrees Celsius. Considering the standard temperature for  the boiling point of acetone is 56.5 degrees Celsius, the range of temperatures at equilibrium during experimentation fell well under this reading. This data suggests such a conservative range would contribute to a more accurate separation between pure vapors and impure substances in the original measurement of acetone.  The sharp melting point range indicates pure acetone was traveling through the distillation apparatus. Consistent equilibrium temperatures indicated that a compound with the same vapor pressure was distilling. Once the equilibrium spiked other impurities with higher vapor pressures were distilling. To obtain an accurate simple distillation it is crucial to stop the experiment once the equilibrium temperature changes.

Infrared Spectroscopy is the means by which the purity of the compound in the distillation experiment was measured. Infrared Spectroscopy deals purely with the infrared section of the electromagnetic spectrum which lies between visible and microwaves. Different bonds or functional groups within a molecule absorb light differently therefore making it possible to determine a compounds purity and possibly an identification. Given the nature and purpose of the experiment, verification of the purity of the substance recovered is a key component. By utilizing infrared spectroscopy in conjunction with melting range of the recovered substance, the purity and identification of the substance can be identified with greater precision and accuracy. After reviewing the graph of the infrared spectroscopy, spikes in the range of 1700 - 1500 wavenumbers (cm-1) (also known as frequency Hz) appear in the recovered acetone, and are not present in the impure acetone which is indicative of possible contaminates due to experimental procedures or laboratory equipment. ﻿ So what specifically does this indicate about your distilled substance?

Taking into consideration the multitude of contaminates present in the solution, a multi-tiered condensation chamber on the distillation apparatus could possibly produce a cleaner, more pure form of the product recovered. The specific molecular characteristics of a compound govern the physical state of a molecule depending on the environmental conditions. By introducing a multi-tiered condensation chamber, the experimenter would be able to separate more contaminates from the pure substance. This would allow contaminates to condense and collect according to their molecular make up.