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[prelab+report] extraction& acid-base properties

Objectives:Give a short description of the goals of this experiment.The goal of extraction & acid-base properties experiment is to know principle of extraction and acid-base properties, separate liquids of sample by using separatory funnel, get solvent which we want.Principles & Methods:1) Extraction- Organic reactions sometimes result in a mixture of organic and inorganic compounds, some of which can differ significantly from the others in the way that they distribute themselves between two immiscible liquids. We can take advantage of such differences in a separation and purification process known as extraction.-Think A is partially soluble in each of two immiscible liquid solvents. After a solution of Ain solvent 1 has been mixed with solvent 2 and shaken, an equilibrium of A between the two phases is established. We can define the equilibrium constant, Kp, known as the distribution, or partition coefficient as the ratio of the concentration of A in phase 2 to its concentration in ph allow us to separate these materials from each other as well as from other neutral organic molecules.-The addition of an acid to a mixture of an organic base and acid will result in the acid remaining uncharged, while the base will be protonated to form a salt. If the organic acid, such as a carboxylic acid, is sufficiently strong, its self-ionization can be suppressed by the added acid.Conversely, the addition of a base to a mixture of an organic acid and base will result in the base remaining uncharged, while the acid is deprotonated to give the corresponding salt. Once again, the self-ionization of a strong base is suppressed by the added base.The acid-base extraction procedure can also be used to separate very weak acids from stronger acids and very weak bases from stronger bases, as long as the difference of their pKa (or pKb) constants is large enough-Usually the pH is adjusted to a value roughly between the pKa (or pKb) constants of the compounds to be separated. Weak acids areany solvents that are immiscible with water do dissolve varying amounts of water. Therefore, prior to any attempt to isolate the solute that has been extracted into an organic solvent, the latter solution should be dried. Drying agents can be added directly to the solution followed by filtration after a suitable period of time. We must consider the intensity, velocity, and capacity of the agent.Table of relevant chemical properties:NameMol. Wt.DensityM.p.B.p.Solubl.OtherBenzoic acid122.121.2659122.41249.21.7Triphenylmethane244.331.01492359insolublemethylene chloride84.9331.3266-96.739.617.5(25 °C)Sodium hydroxide39.99712.133181388418(0°C)Hydrochloric acid(when 38% hcl)1.189-2648Water10100Sodium benzoate144.101.49741062.69(0°C)Sodium sulfate142.042.66488414294.76(0°C)hexane86.180.6548-9668.59.5 mg L−1Results: Summarize the experimental results obtained.1) Benzoic acid eq oac(○,1) After reducing pressure, weight of benzoic acid and filter paper = 0.955g eq oac(○,2) Only filter paper experiment. And we got solvents of respective solution by filtrating or evaporating and then measured melting points of them. Melting points that are measured are similar to literature value of Melting points of them. When all is said and done, we can know that we did accurate experiment.Discussion:Organic reactions sometimes result in a mixture of organic and inorganic compounds, some of which can differ significantly from the others in the way that they distribute themselves between two immiscible liquids. We can take advantage of such differences in a separation and purification process known as extraction. Think A is partially soluble in each of two immiscible liquid solvents. After a solution of A in solvent 1 has been mixed with solvent 2 and shaken, an equilibrium of A between the two phases is established. In most applications of liquid-liquid extraction, the two phases consist of water and an organic solvent. It is both common practice and convenient to arbitrarily classify thevelops, TLC shows us 1 spot, too, because D solution has only DMAP, depending on deionizing by putting NaOH in aqueous layer that is left in process of triphenylmethane extraction. When E solution develops, it shows us 1 spot, because it is solution of Benzoic acid and MC. And we got TLC results that we wanted in this experiment. And we can get benzoic acid in aqueous layer that has benzoic acid ion by putting HCL, deionizing and then filtrating. We can get DMAP by filtrating and evaporating MC (D solution) that has DMAP. Also we can get Triphenylmethane by filtrating evaporating MC (C solution) that has Triphenylmethane. And then we measured melting point of them. Melting points that are measured are similar to literature value of Melting points of them. When all is said and done, we can know that we did accurate experiment.However, we make errors in this experiment. Melting point of Triphenylmethane is measured lower 10℃ than literature value of melting point of it. It can occur, wh

자연과학| 2015.04.21| 2페이지| 1,000원| 조회(356)

산염기, 유기화학, 레포트, 추출, 유기화학실험, 프리랩, extraction&ac..

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[prelab+report] [English] Column chromatography, rotary evaporation

Objectives: Give a short description of the goals of this experiment.The goal of Column chromatography, use of a rotary evaporator experiment is to know principle of Column chromatography and rotary evaporator, separate components of sample by using Column chromatography, get solvent which we want and identify unknown sample by using rotary evaporator and principle of it.Principles & Methods:1) Chromatography- When solute is polar, if stationary phase is polar, the attraction works between each other and solute tends not to deviate from stationary phase.- On the other hand, for the solute, if the mobile phase is polar, solute is melted and diffused band form. The degree of adsorption on the stationary phase and that of elution on the mobile phase are different for each substance, it means that each movement speed is also different.- Chromatography is how to separate samples in mixed liquid by using the stationary phase, the mobile phase and the difference between moving speed of sampleall amount of solvent to displace any air pockets at the bottom and additional solvent is added to refill the column. Next, the dry adsorbent, or a slurry of the adsorbent in solvent, is slowly added to the column and allowed to sift gently down through the solvent to produce uniform packing.-Excess solvent should be carefully drained, but not so the liquid level is allowed to go below the upper level of the adsorbent or channels and air pockets can result, which will cause serious deterioration of resolution.-The stopcock is then opened, and when the liquid level has just reached the top of the adsorbent, fresh solvent is added, and the eluent is collected. For reasons already stated, the top of the column should never be allowed to go dry.-The components of the mixture are resolved and eluted either by continuing to pass the same solvent through the column, isocratic elution, or by use of increasingly polar solvents in a stepwise sequence, stepwise elution.-All solvents used in adsora means rapidly concentrating solutions under mild conditions to overcome problem of distillation that it has the disadvantage of being slow, and the residue, if subjected to an extended period of heating, may decompose.- The boiling point of a liquid is that temperature at which the vapor pressure of the liquid is equal to the total pressure being exerted on the surface. The boiling point is lower when external pressure is lower. So, solvent can evaporate without heating.Table of relevant chemical properties:NameMol. Wt.DensityM.p.B.p.Solubl.Otherbiphenyl154.211.0469.22554.45naphthalene128.170.962580.26217.9731.6(25 °C)Triphenylmethane244.331.01492359insolublehexane86.180.6548-9668.59.5 mg L−19-fluoreneone1801.1383341.5insolublemethylene chloride84.9331.3266-96.739.617.5(25 °C)Results: Summarize the experimental results obtained.2) Rf valueUnknown sample rf = 1.92cm/3.9cm = 0.52-nitrophenol = 0.28cm/4cm = 0.073) Evaporation eq oac(○,1)After evaporation r.b.f taring = 96.549g eq oattention the form of column as well as kind of the stationary phase and the mobile phase, because it influences too separation of materials. First, give cotton under column. This is to prevent a silica gel or sand escaping when loading. Second, about 1/8 inch of sand is added to form a suitable platform for the adsorbent. With the stopcock closed, the vertical column is then filled with a non-polar solvent and then the stopcock should be opened to allow a small amount of solvent to displace any air pockets at the bottom and additional solvent is added to refill the column. Next, the dry adsorbent, or a slurry of the adsorbent in solvent, is slowly added to the column and allowed to sift gently down through the solvent to produce uniform packing. In column chromatography, the most important thing is keeping adsorbent flat. When giving eluent, it makes materials go down equally as time passed. If not, can’t separate perfectly materials. So, when loading, to prevent silica gel being caved of hexane:mc=95:5 at first to separate unknown sample first. Because unknown sample is one of biphenyl, naphthalene, Triphenyl methane, they has lower polar than 2-nitrophenol. And then we use high polar eluent that 100% mc to elute 2-nitrophenol. We check whether all materials come out or not by using TLC. Unknown sample is detected in only 3 test tube. Rf value is 0.5. 2-nitrophenol comes out perfectly in 19 test tube. Because no residue is detected any more after 19 test tube. Rf of 2-nitrophenol is 0.07. To get unknown sample solute, we evaporate 3 test tube. Rotary evaporator lowers boiling point by applying pressure and then makes easy, quick evaporation. Before evaporation, weight of r.b.f is 96.376g. After evaporation, weight of r.b.f is 96.549g. The gap is 0.173g. Yield is 173%. Cause of error is that because we can’t perfectly evaporate sample, so we weigh solute with solvent. And we check melting point sample to identify. Melting point of unknown sample is 69℃-70℃. Melting T

자연과학| 2015.04.21| 2페이지| 1,000원| 조회(216)

영어레포트, 유기화학실험, column chromatograph, rotary..

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[프리랩+결과] [영문레포트] 분별증류, Fractional distillation 평가A+최고예요

Objectives: Give a short description of the goals of this experiment.The goal of simple and fractional distillation experiment is to know accurate definition of boiling point, comprehend principle of distillation and gas chromatography, learn and study simple and fractional distillation method and related techniques and distill solution in hand.Principles & Methods:1) Boiling points- The boiling point of a liquid is that temperature at which the vapor pressure of the liquid is equal to the total pressure being exerted on the surface.- The normal boiling point is defined for a total pressure of 1atm or 760mm Hg.2) Pressure Effects on Boiling Points- A change in the total pressure over the surface of a liquid will have a marked effect on the boiling point.- Because Vapor pressure versus temperature data for a specific compound may not be available in sufficient detail, methods of approximation must be used to obtain boiling-point information at pressures other than 760mm Hg.- The use of mixture, the quantity of material available, the tendency of the material to decompose, and the differences between boiling points of the components.4) Vapor Pressure Effects – Nonvolatile solutes- A high vapor pressure corresponds to a low boiling point.-If a soluble but nonvolatile substance is dissolved in a liquid, the number of liquid molecules able to pass into the gas phase from the liquid surface is reduced. Thai is, the vapor pressure of the liquid is lower and it means the boiling point of such a solution is higher.-Despite this lower vapor pressure, the vapor still consists only of solvent molecules, and condensation of that vapor will result in a complete separation of the solvent from the nonvolatile component.5) Raoult’s Law-Because an ideal solution is one in which there are no solvent-solute interactions, few solutions are completely ideal, but some solutions are approximately ideal. When consider an ideal solution of two liquids, A and B, the vapor pressure of liquid iquid by the fractional distillation is based on the fact that when liquid mixture is evaporated partially, evaporated vapor has more volatile solutes than the original liquid.-If condense the new vapor and again evaporate that several times, the vapor will eventually be pure, will be the vapor that has the low boiling point. But such distillation is so difficult to replay that use fractionation column, or fractional distillation column.7) Enrichment Factor- The enrichment factor is expressed as the quotient of the ratio of components in the vapor phase to their ratio in the liquid phase for a simple distillation.Table of relevant chemical properties:NameMol. Wt.DensityM.p.B.p.Solubl.OtherAcetone58.0890.7929-94.656.5miscibleEthanol46.0790.789-11478.32Results: Summarize the experimental results obtained.Discussion: This section should discuss your interpretation of the experimental results. Did the experiment work? Are your results in line with the expected results for this experiment, the separation and purification of liquids, depending on differences in the vapor pressures of components of a liquid mixture, the quantity of material available, the tendency of the material to decompose, and the differences between boiling points of the components. It uses principle that when heat two liquids having different boiling point each and being well mixed, the component that has low boiling point boils out first, the component that has high low boiling point boils out later. So, through taking each vapor produced from the boil process and cooling them, we can get components that are separated and we want.When distillate liquids mixture that is well mixed and has slightly difference in the boiling point, first boiling component (low boiling point component) and a component (high boiling point component) coming out later appear mixed in vapor. Simple distillation cannot separate perfectly them. So we use fractional distillation that after receiving a material from the distilloint reaches condensation and then is separated.When we use simple distillation, first drop comes out 56°C, uniform sections are 62°C and over 77°C and we can get the result of 22.5ml, not 25ml. When we use fractional distillation, first drop comes out 56°C, uniform sections are 60°C -62°C and over 77°C. The results are slightly different from reported literature values. The boiling point of acetone is 56.5°C and that of ethanol is 78.5°C. Starting points of two methods are pretty similar to literature values. But boiling sections are so different, +6 in simple distillation and +4-+6 in fractional distillation. Moreover, we have failed to obtain the result to 25ml. The error of this difference in temperature can be caused that the temperature is measured by eye. So, we cannot measure the exact temperature at exact volume. And we use clamp that is broken. It means grip is very loose. So, apparatus is not perfectly sealed and we can lose vapor of the sample and heat.The graph that is mad

자연과학| 2015.04.21| 2페이지| 1,000원| 조회(179)

분별증류, 영문, 유기화학실험, 결과, distillation, 프리랩

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$[유기화학실험][프리랩]simple and fractional distillation$

[유기화학실험][프리랩]simple and fractional distillation

Objectives: Give a short description of the goals of this experiment.The goal of simple and fractional distillation experiment is to know accurate definition of boiling point, comprehend principle of distillation and gas chromatography, learn and study simple and fractional distillation method and related techniques and distill solution in hand.Principles & Methods:1) Boiling points- The boiling point of a liquid is that temperature at which the vapor pressure of the liquid is equal to the total pressure being exerted on the surface.- The normal boiling point is defined for a total pressure of 1atm or 760mm Hg.2) Pressure Effects on Boiling Points- A change in the total pressure over the surface of a liquid will have a marked effect on the boiling point.- Because Vapor pressure versus temperature data for a specific compound may not be available in sufficient detail, methods of approximation must be used to obtain boiling-point information at pressures other than 760mm Hg.- The use of a vapor pressure-temperature nomograph allows a rapid estimate of the boiling point at reduced pressure if a normal boiling point is known or an estimate of the normal boiling point if the boiling point at reduced pressure known.3) Distillation- Distillation is a widely used technique for the separation and purification of liquids, depending on differences in the vapor pressures of components of a liquid mixture, the quantity of material available, the tendency of the material to decompose, and the differences between boiling points of the components.4) Vapor Pressure Effects – Nonvolatile solutes- A high vapor pressure corresponds to a low boiling point.-If a soluble but nonvolatile substance is dissolved in a liquid, the number of liquid molecules able to pass into the gas phase from the liquid surface is reduced. Thai is, the vapor pressure of the liquid is lower and it means the boiling point of such a solution is higher.-Despite this lower vapor pressure, the vapor still consists only of solvent molecules, and condensation of that vapor will result in a complete separation of the solvent from the nonvolatile component.5) Raoult’s Law-Because an ideal solution is one in which there are no solvent-solute interactions, few solutions are completely ideal, but some solutions are approximately ideal. When consider an ideal solution of two liquids, A and B, the vapor pressure of liquid A can be described by Raoult’s law. A similar equation will apply to liquid B.-The mole fraction is defined in the usual manner.-The total pressure, Pt=Pa+Pb and the boiling point is reached when Pt is equal to the pressure exerted on the surface of the liquid.-But the most of solutions in world is not ideal, so the vapor of them does not follow Raoult’s Law.6) Fractional distillation-Separation of the liquid by the fractional distillation is based on the fact that when liquid mixture is evaporated partially, evaporated vapor has more volatile solutes than the original liquid.-If condense the new vapor and again evaporate that several times, the vapor will eventually be pure, will be the vapor that has the low boiling point. But such distillation is so difficult to replay that use fractionation column, or fractional distillation column.7) Enrichment Factor- The enrichment factor is expressed as the quotient of the ratio of components in the vapor phase to their ratio in the liquid phase for a simple distillation.Table of relevant chemical properties:NameMol. Wt.DensityM.p.B.p.Solubl.OtherAcetone58.0890.7929-94.656.5miscibleEthanol46.0790.789-11478.32Results: Summarize the experimental results obtained.Discussion: This section should discuss your interpretation of the experimental results. Did the experiment work? Are your results in line with the expected results for this experiment, or are they different? If you have the results that you expected, what do those tell you about the property/reaction/method you studied in this experiment? If your results are not what you expected, indicate why you think your results are unexpected and, if applicable, explain why you did not get the expected results (probable cause of errors, accidents, etc.).[ If a question was given for this experiment, also answer it in this section. ]Name & ID:Date:Lab Group # :Experiment Name:PRELABName & ID:Date:Lab Group # :Experiment Name:LAB REPORT

자연과학| 2015.03.24| 2페이지| 1,000원| 조회(398)

증류, 가스크로마토그래피, 유기화학실험, simple distillation, distillation

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[유기화학실험][프리랩+결과]determination of melting point&TLC(thin-layer chromatography) 평가A+최고예요

Objectives: Give a short description of the goals of this experiment.1) The goal of determination of melting point experiment is to know accurate definition of melting point and melting range, learn how to measure them, know difference between melting point of pure compound and that of mixture and identify unknown sample by using difference between melting point of pure compound and that of mixture.2) The goal of thin-layer chromatography of analgesics experiment is to comprehend principle of TLC, learn how to use TLC and identify unknown analgesics by using TLC.Principles & Methods:*Determination of melting point1) Melting point and Melting range- The melting point of a pure compound is temperature at which the solid and liquid phases are in equilibrium as some particular pressure. It means that a minute change in temperature causes a change in the state of a solid in a liquid or in the state of a liquid in a solid.- The melting range is temperature range up to the point from where anng bath at a temperature below the melting point to avoid this problem, the melting point is measured Therefore shall heating bath at a temperature below the melting point to avoid this problem, the melting point to be measured before the decomposition occurs rapidly before the decomposition occurs.* Thin-layer chromatography of analgesics1) Partition equilibrium- Polar solvent and non-polar solvent isn’t mixed by ‘like dissolves like’ principle. When the solvents are mixed and then are separated into layers, non-polar solute is mixed better in non-polar solvent than polar solvent. With this, when the temperature and pressure are fixed and any substance melts in non-polar solvent and polar solvent, the extent to which substance dissolved is the distribution coefficient.- Partition equilibrium is based that distribution coefficients of substances are different.2) Chromatography- When solute is polar, if stationary phase is polar, the attraction works between each other and solute tends tion should discuss your interpretation of the experimental results. Did the experiment work? Are your results in line with the expected results for this experiment, or are they different? If you have the results that you expected, what do those tell you about the property/reaction/method you studied in this experiment? If your results are not what you expected, indicate why you think your results are unexpected and, if applicable, explain why you did not get the expected results (probable cause of errors, accidents, etc.).The melting point of a pure compound is temperature at which the solid and liquid phases are in equilibrium as some particular pressure. It means that a minute change in temperature causes a change in the state of a solid in a liquid or in the state of a liquid in a solid and the melting range is temperature range up to the point from where any compound starts to melt to where it melt completely. Measurement of melting point and range of Benzoic acid and Acetanilide each material has same melting point of material and compound. But if two compounds are not same, compound has broad range of temperatures and lower melting point, because the other compound acts as impurities. But, when melting points are same, do not conclude two materials are same, because they can be a solid solution.Melting point of unknown sample that is measured in this experiment is similar to melting point of cinnamic acid among melting points of three samples. We can see they are same or not by measuring melting point of unknown sample and cinnamic acid. If the prediction is correct, the melting point that is measured is similar to melting point of cinnamic acid. If the prediction is not correct, the melting point is lower and the melting range is wider than that of cinnamic acid, because each compound acts as impurities to each other. The result of measurement is 126℃~130℃. It is a little different to melting range of cinnamic acid. But we measure that fast, so there are erre rate using them, called Rf. Rf can be calculated ‘the distance traveled component material/ the distance traveled mobile phase’. We calculated Rf of samples and identified unknown compound basing on this principle.Only fast green was not separated in EtOAc eluent, because it has relatively stronger adsorptive power than other samples. So, to separate fast green, make EtOAc:MeOH one-to-one ratio eluent that EtOAc is relieved out and put MeOH that has more polarity than EtOAc to be more polar and develop. The point to note is that if put too much MeOH, silica gel used as the stationary phase is so polar that melts. It means resolving power lowers. Anyway, polarity big order that is expected is ‘Fast green, Rhodamin B, Bismakr brown, Sudan IV’. Because the longest moving distances of sample in strong polar silica gel means the sample has the lowest polarity in samples, according to the principle of first paragraph. However, when developed in EtOAc:MeOH one-to-one ratio eluent, fast greePORT

자연과학| 2015.03.24| 3페이지| 1,000원| 조회(356)

크로마토그래피, Chromatography, TLC, 녹는점, 유기화학실험, Me..

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