Internet gaming, latest technology, coolest gadgets, online freebies and day to day college life.
Here are the presentation I’d make for our report with regards to the Determination of Mutual Solubility of Phenol - Water.
It only includes the objective and the procedure of the experiment.
Feel free to see.
Partially Miscible Liquids: Determination Of Mutual Solubility Presentation 2008
Physical Chemistry Experiment
Abstract
A phenol - water solution was used to determine the solubility of two partially miscible liquids. The group calculated the volume of water required to prepare the following mixtures with volume percentage ranging from 5% to 95% sample at 5% increment using 10mL phenol sample. The different volume ratios of mixtures prepared were subjected to constant heating and cooling in order to gather the needed temperature necessary for the construction of the mutual solubility curve of Phenol- Water solution. The critical solution temperatures were determined at 30% Phenol - 70% Water ratio, 64˚C (for single phased region) and 61.8˚C (for double - phased region)…
I. Introduction
Oil and water don’t mix. Pouring 10 mL of olive oil into 10 mL of water results in two distinct layers, clearly separated by a curved meniscus. Each layer has the same volume and essentially the same composition as the original liquids. Because very little mixing has apparently occurred, the liquids are called “immiscible” or unmixable.
Pouring grain alcohol into water results in a single liquid phase. No meniscus forms between the alcohol and the water, and the two liquids are considered “miscible”. Nearly any pair of liquids is miscible if only a trace amount of one of the liquids is present.
Many liquid mixtures fall between these two extremes. Two liquids are “partially miscible” if shaking equal volumes of the liquids together results in a meniscus visible between two layers of liquid, but the volumes of the layers are not identical to the volumes of the liquids originally mixed. For example, shaking water with certain organic acids results in two clearly separate layers, but each layer contains water and acid (with one layer mostly water and the other, rich in acid.) Liquids tend to be immiscible when attractions between like molecules are much stronger than attractions between mixed pairs. (Logan, 1998)
The objectives of this experiment are 1) to determine the solubility of two partially liquids (phenol - water solution), 2) to construct a mutual solubility for the pair, and 3) to determine their critical solution temperature.
II. Review of Related Literature
Mutual solubility of polymers and properties of their mixtures
“Heats of mixing of polymers with each other have been measured, the behavior of the mixtures of solutions of various polymers has been studied, and the dependence of mechanical properties of polymer mixtures on the ratio of components has been investigated. It has been shown that mixing of polymers with each other is usually an endothermic process and, therefore, leads to formation of macroscopically homogenous, but actually microheterogenous, systems with an extremely high degree of dispersion. These microheterogenous polymer mixtures are formed because of the enormous viscosity of polymer mixtures, which prevents macroscopic separation into phases but does not hinder the considerable mobility of the segments of flexible chain molecules. It has been shown that the dependence of mechanical properties of microheterogenous polymer mixtures on the ratio of polymers in the mixture have sharp maxima or minima which cannot be found in the case of true polymers in polymer solutions. It has been found that the behavior of some polymer pairs is anomalous, in that exothermal mixing is supplemented by separation of the solution mixture into phases and by the appearance of maxima or minima in the dependences of the properties of polymer mixtures on the ratio of polymers in the mixture. This anomaly has been attributed to the effect of loose packing of the molecules of the polymers which show anomalous behavior. It has been shown that, in these systems, there necessarily exists a lower critical temperature of mixing whose value can be decreased by adding low-molecular solvents to the loosely packed polymer. Attention has been drawn to the fact that, although mixing of amorphous polymers should be considered on a thermodynamic basis to be a mutual solution of two liquid phases, the large dimensions and the flexibility of polymer chain molecules require a critical revision of the possibility of formal application of the basis thermodynamic concepts and relations to a theoretical analysis of the behavior of polymer mixtures.” (Slonimski, 1998)
Equations of state for the calculation of fluid-phase equilibria
“Progress in developing equations of state for the calculation of fluid-phase equilibria is reviewed. There are many alternative equations of state capable of calculating the phase equilibria of a divers (Sadus and Song Wei)e range of fluids. A wide range of equations of state from cubic equations for simple molecules to theoretically-based equations for molecular chains is considered. An overview is also given of work on mixing rules that are used to apply equations of state to mixtures. Historically, the development of equations of state has been largely empirical. However, equations of state are being formulated increasingly with the benefit of greater theoretical insights. It is now quite common to use molecular simulation data to test the theoretical basis of equations of state. Many of these theoretically-based equations are capable of providing reliable calculations, particularly for large molecules.” (Sadus and Ya, 2000)
Mutual solubility study for 94.2:5.8 of ethanol to octane with supercritical carbon dioxide solvent
“Solubility data of a mixture containing 94.2% ethanol and 5.8% octane was measured in carbon dioxide solvent using a high-pressure type phase equilibrium apparatus at pressures up to 103.5 bar and at temperature of 75 °C. The results showed that considerable separation was not achieved in this ethanol and octane ratio. However, the experimental data were then compared with the theoretical data which were obtained from two models which are regular solution theory and Redlich-Kwong equation of state. Regular solution theory is employed to each phase by applying activity coefficient expressions. Redlich-Kwong equation of state is employed to the vapor phase and then with applying fugacity coefficient, liquid phase data is obtained. The regular solution theory as a novel model approach has been found to be encouraging for the prediction of phase equilibria solubilities. It concluded that the regular solution theory model could predict two phases equilibrium data better than Redlich-Kwong equation of state.” (Davarnejad et al, 2008)
Solubility, miscibility and their relation to interfacial tension in ternary liquid systems
“The terms, miscibility and solubility, are widely used in phase behavior stud (Ayiralam and Rao)ies of multicomponent hydrocarbon systems. The distinction between these two terms appears to be still hazy, leading to their synonymous use in some quarters. Also, the relation of these two thermodynamic properties with interfacial tension has largely remained unexplored. However, recently a new experimental technique of vanishing interfacial tension (VIT) has been reported relating miscibility with interfacial tension in gas-oil systems. Therefore, the objectives of this study are to correlate miscibility and solubility with interfacial tension and to investigate the applicability of the new VIT technique to determine miscibility conditions in ternary fluid systems. For this purpose, a standard ternary liquid system of benzene, ethanol and water was chosen since their phase behavior and solubility data were readily available. The interfacial tensions of benzene in aqueous ethanol at various ethanol enrichments were measured using the drop shape analysis (DSA) and capillary rise techniques.
The experimental results indicate the applicability of VIT technique to determine miscibility conditions for ternary liquid systems as well. Comparison of IFT measurements with solubility data showed a strong mutual relationship between these two properties, in addition to demonstrating a clear distinction between solubility and miscibility. The interfacial tension appears to be independent of solvent-oil ratio in feed, provided that complete equilibration of fluid phases is allowed to incorporate all the mass transfer effects during experimentation. All these experimental observations have immense application in fluid-fluid phase equilibria studies and to determine the miscibility conditions of gas injection improved oil recovery projects.” (Ayiralam et al, 2006)
Heats of mixing of the partially miscible liquid system cyclohexane + methanol
“The molar excess enthalpies of cyclohexane + methanol were systematically measured with a Picker flow microcalorimeter operated in the discontinuous mode at 298.15, 303.15, 308.15, 313.15, 318.15 and 323.15K. Our measurements are higher than the literature data. This work shows that molar excess enthalpies increase with temperatures, an the straight segments of the excess enthalpy curves in the mid region become shorter with increasing temperature. At 323.15K the curve become one of a miscible liquid system, and the position of the maximum value is at X=0.6. In addition, the calorimetric measurement can be used to determine the compositions of two immiscible phases for the binary mixture.” (Dai and Chao, 1985)
III. Methodology
Apparatus and Materials
Phenol Sample
Distilled water
Stirring Rod
Hot plate
200ml beaker
Thermometer (0.1 deg calibration)
1 L Beaker (2pcs)
A. Preliminaries
Before the experiment, the group calculated the volume of water required to prepare the following mixtures with volume percentage ranging from 5% to 95% sample at 5% increment, using 10mL sample in each proportion. The calculations should be approved before proceeding.
B. Experiment Proper
After the preparation of a 95% sample - 5% water volume to volume mixture based on 10mL of the sample, [Caution: All the samples are corrosive while triethylamine is flammable, a lachrymator and readily forms explosive in air] the mixtures was heated in a water bath with mild stirring until the cloudiness in it disappears. Its temperature was noted. It was cooled in a second water bath with mild stirring until the cloudiness appears. Once again, the temperature was noted. This process was repeated until a fairly constant reading was observed for a specific volume ratio mentioned in the preliminaries. Constant temperature was recorded.
IV. Data and Discussion
After the group prepared a 95% phenol -5% water volume to volume mixtures based on 10mL of the sample (see Table I), the mixture was heated in a water bath with mild stirring and recorded its constant temperature until the cloudiness of the solution disappeared and cooled instantly until the cloudiness appears. As shown in Table I, it shows that on 95% phenol - 85% phenol and 5% phenol, there is no significant changes appeared both for heating and cooling of the mixtures due to the concentration of phenol in the solution. Cloudiness of the solution started to appear at 80% phenol.
Table I: The prepared amount of water needed to add at the given
percentage of Phenol - Water Solution based on 10ml sample
|
% Phenol by Volume |
Volume of Added Water / mL |
|
95 |
0.53 |
|
90 |
0.59 |
|
85 |
0.65 |
|
80 |
0.74 |
|
75 |
0.83 |
|
70 |
0.95 |
|
65 |
1.10 |
|
60 |
1.28 |
|
55 |
1.52 |
|
50 |
1.81 |
|
45 |
2.22 |
|
40 |
2.78 |
|
35 |
3.57 |
|
30 |
4.76 |
|
25 |
6.67 |
|
20 |
10.00 |
|
15 |
16.67 |
|
10 |
33.33 |
|
5 |
100.00 |
Based on the data in Table II, the group constructed the mutual solubility curve for Phenol - Water solution which is important in the determination of the critical temperature of the mixture. Critical solution temperature is the temperature at which a mixture of two liquids (Phenol and Water for this experiment), immiscible at ordinary temperatures, cease to separate into two distinct phases. The black line symbolizes the temperature reading of phenol in the hot water bath while the gray line is the temperature reading of phenol in the cold water bath.
On the other hand, the red curve is the polynomial trend line of mixture in the hot water bath in which the solution tends to become in single phased (no cloudiness appeared), while the blue curve is the polynomial trend line of the cooled mixture that tends to start the double phased region (appearance of cloudiness). The critical temperatures of the solution was located at 30% phenol - 70% water, 64˚C (heating) and 61.8˚C (cooling).
Table II : Constant temperature reading of Phenol - Water Solution at heating and cooling process on 10ml sample.
|
% Phenol by Volume |
Constant Temperature Reading /˚C |
|
|
HEATING |
COOLING |
|
|
95 |
no change appeared |
no change appeared |
|
90 |
no change appeared |
no change appeared |
|
85 |
no change appeared |
no change appeared |
|
80 |
36.3 |
32.8 |
|
75 |
41.2 |
35.2 |
|
70 |
43.7 |
39.7 |
|
65 |
46.8 |
42.9 |
|
60 |
52.5 |
47 |
|
55 |
53 |
50.9 |
|
50 |
54.2 |
52.4 |
|
45 |
58.5 |
56.7 |
|
40 |
65.2 |
62.2 |
|
35 |
68.7 |
66.1 |
|
30 |
64 |
61.8 |
|
25 |
60.4 |
56.2 |
|
20 |
54.9 |
50.7 |
|
15 |
51.3 |
47.2 |
|
10 |
48.5 |
43.6 |
|
5 |
no change appeared |
no change appeared |
Figure 1. Mutual Solubility Curve of Phenol - Water Solution
V. Conclusion and Recommendation
Throughout the experiment, the critical solution temperature of the solution was 64˚C (heating) and 61.8˚C (cooling) at 30% phenol - 70% water. There are factors that affect the solubility of the mixtures, the nature of solute and solvent, the temperature and the pressure.
a) Nature of Solute and Solvent
b) Temperature
If the solution process absorbs energy, then the solubility will be Increased as the temperature is increased. If the solution releases energy, then the solubility will Decreased with increasing temperature.
c) Pressure
If solid and liquid, there is no change in solubility if pressure changes, likewise, in gas, as pressure increased, solubility also increases.
Cloudiness is significant in this experiment for immiscible liquids. Through cloudiness, we cansay that the substance is still unmix due to the presence of stable emulsion, but when a completely clear solution with no trace of cloudiness, we can assume that the substance is mixed
Ayiralam, Subhash C. and Dandina N. Rao. “Solubility, miscibility and their relation to interfacial tension in ternary liquid systems.” Fluid Phase Equilibria 249.1 (2006): 82-91.
Dai, Ming and Jian-Ping Chao. “Heats of mixing of the partially miscible liquid system cyclohexane + methanol.” Fliuid Phase Equilibria 23.2 (1985): 315-319.
Davarnejad, R, K.M Kassim and A Zainal. “Mutual solubility study for 94.2:5.8 of ethanol to octane with supercritical carbon dioxide solvent.” Journal of the Chinese Institute of Chemical Engineers 39.4 (2008): 343-352.
Logan, R.S. “The Behavior of a Pair of Partially Miscible Liquids.” Chemical Education 75.339 (1998): 206-208.
Sadus, Richard J and Ya Song Wei. “Equations of state for the calculation of fluid-phase equilibria.” AIChE 46.1 (2000): 169-296.
Slonimski, G.L. “Mutual solubility of polymers and properties of their mixtures.” Journal of Polymer Science 30.121 (1958): 625 - 637.
Analytical Chemistry Experiment
Preparation of Alcoholic Beverages from Fresh Fruits
Abstract
About one kilogram of Pineapple was washed, peeled and cut off in small cube to osterize in a blender. A fruit extract was obtained. Together with the addition of desirable amount of sugar and yeast, the fruit extract was placed in a high-neck bottled and been fermented for at least two weeks. It was been pastured through the use of traditional katsa (filter). Pineapple wine was produced and placed to observation about its taste, color, odor, textured and transparency . 100ml of the wine with raisins was set aside for distillation and boiling point experiments…
I. Introduction
Fermentation come form a Latin word fermentum means to leaven. Fermentation is the anaerobic enzymatic conversion of organic compounds, especially carbohydrates, to simpler compounds, especially to ethyl alcohol, resulting in energy in the form of adenosine triphosphate (ATP); the process is used in the production of alcohol, bread, vinegar, and other food or industrial products. It differs from respiration in that organic substances rather than molecular oxygen are used as electron acceptors. Fermentation occurs widely in bacteria and yeasts, the process usually being identified by the product formed; e.g., acetic, alcoholic, butyric, and lactic fermentation are those that result in the formation of acetic acid, alcohol, butyric acid, and lactic acid.
On the other hand, fermentation can also define as the conversion of a carbohydrate such as sugar into an acid or an alcohol. More specifically, fermentation can refer to the use of yeast to change sugar into alcohol or the use of bacteria to create lactic acid in certain foods. Fermentation occurs naturally in many different foods given the right conditions, and humans have intentionally made use of it for many thousands of years.
II. Review of Related Literature
Alcoholic Beverages
May be divided into fermented drinks including beer and wines, and distilled drinks or spirits which are obtained from the former by distillation. Spirits usually contain about fifty per cent. of alcohol, beer and wines from one to twenty per cent. The alcohol in all cases results from the breaking up of the sugar in the fermenting liquid.
Sugars
Ordinary sugar, or cane sugar, uncrystallizable, or fruit sugar; and grape sugar, or glucose, are the three most important varieties. Fruit sugar exists in all the sub-acid fruits as grapes, currants, apples, peaches, etc. When these are dried, it changes to grape sugar forming the whitish grains which are seen on the outside of prunes, raisins, etc. Grape sugar is found to a limited extent in fruits associated with fruit sugar. Cane sugar is readily changed by the action of acids or ferments into fruit sugar, and the latter into grape sugar, but the process cannot be reversed. Grape sugar is the only fermentable variety, the others becoming changed into it before fermentation.
Transformation of Starch
Under the influence of acids, or diastare, a principle existing in germinating grains, starch is changed first into gum (dextrine) and afterwards into grape sugar. Hence one of our most important sources of alcohol is to be found in the starch of barley, corn, wheat, potatoes, etc. Wood may be converted into grape sugar by the action of strong sulphuric acid which is afterwards neutralized. An attempt to produce alcohol in this way on a commercial scale was made in France, but was not successful.
Ferment
A solution of pure sugar will remain unchanged for an indefinite period of time. To induce fermentation, a portion of some nitrogenous body, itself undergoing decomposition, must be added. Such ferments are albumen (white of egg), fibrin (fibre of flesh), casein (basis of cheese), gluten (the pasty matter of flour). Yeast consists of vegetable egg-shaped cells, which is increased during its action as a ferment.
Circumstances influencing Fermentation
In order that fermentation shall begin we require, besides the contact of the ferment, the presence of air. The most easily decomposed articles of food may be preserved for an indefinite period by hermetically sealing them in jars, after drawing out the air. When once begun, however, fermentation will go on, if the air be excluded. Temperature is important. The most favorable temperature is between 68 and 77 Fahr. At a low temperature fermentation is exceedingly slow. Bavarian or lager beer is brewed between 32 and 46 1/2 Fahr. A boiling heat instantly stops fermentation, by killing the ferment.
To check fermentation we may remove the yeast by filtration. Hops, oil of mustard, sulphurous acid (from burning sulphur), the sulphites, sulphuric acid, check the process by killing the ferment.
Too much sugar is unfavorable to fermentation, the best strength for the syrup is ten parts of water to one of sugar.
Changes during Fermentation
The grape-sugar breaks up into carbonic acid which escapes as gas, alcohol and water which remain. In malting the grain is allowed to germinate, during which process the starch of the grain is changed into gum and sugar: the rootlets make their appearance at one end and the stalk or acrospire at the other. The germination is then checked by heating in a kiln; if allowed to proceed a certain portion of the sugar would be converted into woody matter, and lost.
In brewing the sacharine matter is extracted from the malt during the mashing. Yeast is added to cause fermentation; an infusion of hops afterwards, to add to the flavor and to check fermentation. In wine making there is sufficient albuminous matter in the grape to cause fermentation without the use of yeast.
Distillation separates the alcohol in great part from the water. Alcohol boils at 179 Fahr., and water at 212. It is not possible, however, to separate entirely alcohol and water by distillation.
(The Household Cyclopedia of General Information, 1881)
III. Methodology
A. Preparation of Juice Extract
1.) Wash 1k of fruit. Peel off skin, or remove the seeds or pits when present. Cut small cubes, and osterize into a smooth consistency using a blender.
2.) Add boiled water (cooled before adding). If the fruit extract obtained is viscous or too thick in consistency.
3.) Add about brown or white sugar (amount added is relative to your taste) as he fruit is osterized and mixed thoroughly.
4.) Transfer the juice into a high-necked bottle and cover tightly.
B. Fermentation
1.) Follow the set-up given by the instructor.
2.) Add about 2 tablespoons of yeast to the fruit extract.
3.) Allow fermentation of the mixture for 2-3 weeks.
C. Pasteurization
1.) Using clean cheesecloth (katsa), filter the fermented mixture, receiving the filtrate in a clean container.
2.) Warm the filtrate to about 60-65 C. Add raw egg white and stir until the egg white is cooked. The egg white acts as a coagulant for any left-over residue in the filtrate.
3.) Filter the cooked mixture again, using the cheesecloth. Dispose any coagulated substance retained by the cloth.
4.) Place a small amount of the fermented mixture in a clean container and observe the following properties:
a.) taste b.) color c.) odor d.) texture e.) transparency
5.) Set aside 100ml of the fermented mixture for the distillation and boiling point experiments. Keep this portion in a tightly sealed bottle and refrigerate.
IV. Discussions of Data and Interference from Results
After doing the experiment, we observed the following properties:
|
Taste |
Sweet pineapple taste with pinch of an alcoholic taste.
|
|
Color |
It comes in bright yellow in color.
|
|
Odor |
Strong Pineapple. Too much smell can make you feel dizzy.
|
|
Texture |
It was just fine.
|
|
Transparency |
It comes in a slimy bright yellow . I think sugar is the cause why it is slimy.
|
The wine was alcoholic because of the sugar or glucose that was broken down by the yeast. Without the presence of oxygen, the product of the glucose becomes ethyl alcohol and carbon dioxide.
V. Answers to Guide Questions
1.) Write the balanced chemical equation that represents the fermentation of sugar.
C6H12O6 → 2 C2H5OH + 2 CO2
This chemical equation summarizes ethanol fermentation, in which one hexose molecule is converted into two ethanol molecules and two carbon dioxide molecules
2.) What is the role of the yeast in the process?
Yeast are unicellular fungi that reproduce asexually by budding or fission. Yeast is what causes primary fermentation to take place. The role of yeast in the chemical process is that it will eat the sugars in the pineapple juice and the end products are CO2 and alcohol.
3.) Why should the fermentation set-up be alright?
Set-up should be alright in order to have accurate result of the experiment since fermentation is an anaerobic process, and oxygen will cause the organisms to produce different products.
If the set-up for fermentation is not properly assembled, like if the cover in the set-up is not properly sealed, the result of the fermentation may be contaminated or worse if the fermentation process will not take effect because of the presence of oxygen converting glucose to carbon dioxide and water.
4.) What is the use of the limewater in the process?
Lime water also known as saturated calcium hydroxide solution Ca(OH)2 can be used to test the presence of carbon dioxide because lime water reacts with carbon dioxide to produce a precipitate of calcium carbonate:
Ca(OH)2 (aq) + CO2 (g) → CaCO3 (s) + H2O (l)
Lime water is also used in fermentation, to determine whether carbon dioxide was produced. When lime water reacts with CO2 it becomes milky.
5.) What must be the average pH of the product of fermentation to qualify as “alcoholic”?
The resulting alcohol is 100 to 200 proof (200 proof is pure alcohol). Yeasts are able to grow in foods with a low pH, (5.0 or lower) and in the presence of sugars, organic acids and other easily metabolized carbon sources.
VI. Bibliography
Analytical Chemistry Experiment
Simple Distillation Method
Abstract
A quick fit set-up for simple distillation was been assembled carefully. 50ml of Pineapple wine was placed in a pear shaped flask and added with boiling chips. Making sure that water was flowing in a condenser, the wine sample was heated with a burner using one inch blue flame. Four distillate with recorded temperatures were collected. These distillates were kept for boiling point experiments…
Introduction
The boiling point of a pure organic liquid is a physical property of that liquid. It is defined as the temperature at which the vapor pressure of the liquid exactly equals the pressure exerted on it. Boiling points can be determined using the technique of simple distillation. Distillation is a technique that is used to purify a mixture of liquids or to obtain a boiling point of a pure liquid (in the case of this course). Essentially, the liquid is heated to boiling and the vapors condensed above the boiling liquid.
Distillation is a very old technique which is frequently used to purify compounds and to determine their boiling points. The boiling point is a useful molecular constant for the characterization and identification of pure compounds. Furthermore, the boiling point range is usually a good indicator of the purity of a liquid.
Distillation is a physical process used to separate mixtures that contain at least one liquid. Distillation works because each substance in the mixture has its own unique boiling point. So, as a mixture is heated, the temperature of the mixture rises until it reaches the temperature of the lowest boiling substance in the mixture. The lowest boiling substance boils away. Meanwhile, the other components of the mixture remain in their original phase (either solid or liquid) until the lowest boiling component has all boiled off. Only then does the temperature of the remaining mixture rise and other components are boiled off.
I. Review of Related Literature
Distillation often follows fermentation. Fermentation is used to produce alcoholic beverages. Grain is fermented to make beer, while grape juice is fermented to make wine. Beer and wine never contain more than around 12% alcohol, because any higher concentration kills the yeast that produce the alcohol. To make stronger drink, distillation is used. Wine, beer, or fermented brews made from corn, sugar cane, or potatoes can be purified by distillation. Since ethyl alcohol boils at only 83°C while water boils at 100°C, the alcohol will boil off, leaving the water behind. The alcohol vapors are then condensed and collected. Distillation can produce liquors that range from 40-95% ethyl alcohol.
The object of distillation is the separation of the alcohol from the other ingredients in the beer, mostly water. In making fuel alcohol it is necessary to get all of the alcohol and water separated if the alcohol is going to be mixed with gasoline, and most of the alcohol and water separated if the alcohol is going to be burned in a converted engine. As will be seen, the purer the alcohol, the harder it is to make.
The separation of the alcohol and water by distillation is made possible by the fact that alcohol boils at about 173 degrees F. and water at 212 degrees F. When the mixture of water and alcohol is boiled, vapors with a greater concentration of alcohol will be formed and liquid with a lesser concentration of alcohol will remain behind. However, because water and alcohol do not form what is called an “ideal” mixture, the separation cannot be done in one clean step.
Figure Simple Distillation
It illustrates a simple distillation apparatus using laboratory-type equipment. Note that the equipment consists basically of a container for the liquid to be distilled (still pot), a heat source, and a condenser to turn the distilled vapors back into liquid form. The thermometer is necessary to monitor the temperature of the vapors.
II. Methodology
1.) Carefully assemble the quick-fit set-up.
2.) Place 50ml of the liquid sample in the pear shaped flask. Add a few pieces of boiling chips.
3.) Make sure the water is flowing through the condenser. Heat the sample with a burner, using a one-inch blue flame.
4.) Collect the distillate in labeled test tubes, recording the temperature. Change the test tube after collecting 5 to 10 drops. Keep the distillate for the boiling point determination.
5.) When done, cut off the heat source first, before closing the water valve.
6.) Allow time for the set-up to cool before dismantling the glassware.
III. Discussions of Data and Interference from Results
The data below are from the collected fractions of distillates from the liquid sample. Every fraction contains 1mL of the distillate. We used a test tube containing 1mL of distilled water to compare it with our fraction to know if it contains the right amount of volume we wanted.
|
Volume of fraction collected |
Temperature |
Flame test result |
|
| Fraction 1 |
1mL |
°C |
Not Tested |
| Fraction 2 |
1mL |
°C |
|
| Fraction 3 |
1mL |
°C |
|
| Fraction 4 |
1mL |
°C |
The first fraction we collected with 1mL of the distillate was at __°C, the second at __°C third at __°C and the last is at __°C . We didn’t tested the first fraction if it is flammable or not to know if the distillate was an ethanol or not since our instructor not ask to do it so. But as far as the temperature values are concerned since they are closed to the accepted values boiling ethyl alcohol, I can say that the product is an ethyl alcohol.
IV. Answers to Guide Questions
1.) Where should the thermometer bulb in the distillation setup be placed and why?
The thermometer should be placed above the liquid sample where the vapor is passing. In this case, we can determine the temperature of the vapor and not the liquid sample.
2.) How can one know that a component of liquid mixture has been completely vaporized and distilled over?
One can know that a component of liquid mixture has been completely vaporized and distilled over if, the vapor from the liquid sample turned to pure liquid.
3.) What is the advantage of a fractional distillation over the simple distillation type?
The advantage of fractional distillation over the the simple distillation type is that, in fractional distillation, the separation of a mixture into its component parts, or fractions, such as in separating chemical compounds by their boiling point by heating them to a temperature at which several fractions of the compound will evaporate.
While in simple distillation, all the hot vapors produced are immediately channeled into a condenser which cools and condenses the vapors. Therefore, the distillate will not be pure, its composition will be identical to the composition of the vapors at the given temperature and pressure.
V. Bibliography
Analytical Chemistry Experiment
Determination of the Boiling Point
Abstract
I. Introduction
Several factors enter into determining the boiling point, and the molar heat of vaporization, of a hydrocarbon. Hydrocarbons containing more than 6 carbon atoms in a linear chain depend upon chain entanglement in addition to the factors that also play a role in hydrocarbons containing less than 6 carbon atoms in a linear chain. For the smaller hydrocarbons, the forces holding the liquid together are similar, primarily van der Waals interactions. However, in addition, the degree of non-ideality of the vapor phase, and the globular shape of the molecule. The more symmetric molecules tend to be more volatile.
The boiling point of a liquid is the temperature at which the liquid and vapor phases are in equilibrium with each other at a specified pressure. Therefore, the boiling point is the temperature at which the vapor pressure of the liquid is equal to the applied pressure on the liquid. The boiling point at a pressure of 1 atmosphere is called the normal boiling point.
II. Review of Related Literature
Siwoloboff Method
Principle
A sample is heated gradually in a tube which is immersed in a liquid bath. The sample tube is held in close contact with a thermometer and it contains a boiling capillary which is fused about 1 cm above its lower end. Upon approach of the boiling temperature bubbles emerge rapidly from the lower open end of the capillary. The boiling temperature is that temperature at which, on momentary cooling, the string of bubbles stops and liquid suddenly rises in the capillary.
Procedure
The bath liquid is chosen according to the expected boiling temperature of the test substance. Silicone oil can be used for temperatures up to 573 K. Liquid paraffin may only be used for
Temperatures up to 473 K. At first, the heating of the bath should be adjusted to a temperature rise of 3 K/min. The bath must be stirred. At about 10 K below the expected boiling temperature, the heating is reduced so that the temperature rise is less than 1 K/min. Upon approach of the boiling temperature, bubbles begin to emerge rapidly from the capillary. The boiling temperature is that temperature at which, at momentary cooling, the string of bubbles stops and fluid suddenly rises in the capillary
OECD Guidelines for the Testing of Chemicals 1995
III. Methodology
1.) Prepare 2-3 capillary tubes, sealing one end with the use of a Bunsen burner.
2.) Adapting the simplified Siwoloboff method, place a few drops of the sample in a centrifuge tube. A capillary tube, its sealed end up, is immersed in the sample. The centrifuge tube is then attached to the bulb of the thermometer.
3.) The tube-thermometer is then placed in an oil bath. Add a few pieces of boiling chips to the bath.
4.) Heat the oil bath with a small blue flame, occasionally stirring it, to ensure uniform distribution of heat.
5.) Closely observe and record the temperature at which the first bubble leaves the inverted capillary tube. Then record the temperature when the liquid sample enters the tube, just as the last bubble leaves it. This is the so-called boiling point range.
6.) Do a second trial repeating steps 2 to 5.
IV. Discussions of Data and Interference from Results
|
T1/°C |
T2/°C |
|
| Sample 1 |
72°C |
80°C |
| Barometric Pressure |
765 mmHg |
The sample we used has the range 72°C to 80°C in 765 mmHg, while the boiling point of ethanol in 760 mmHg is 78.5°C. We could not really tell whether the sample we used was pure for we are not in the atmospheric pressure.
V. Answers to Guide Questions
Boiling point of ethyl alcohol is about 78.5 °C and our boiling point ranges between 72 °C to 80 °C.
There are many possible sources of error in this experiment. It can be human error and instrumental error.
One of the causes of errors in determining the boiling point I found which can change our observed value is the barometric pressure. The literature boiling point of ethanol is about 78.5 °C in 760 mmHg while our boiling point was in 765 mmHg.
VI. Bibliography
 |  |  |  |  |  |  |  |  |
 |  |  |  |  |  |  |  |  |
 |  |  |  |  |  |  |  |  |
 |  |  |  |  |  |  | ||
| By N2H | ||||||||
