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순수 액체의 증기압 측정 결과레포트 A+

2.DiscussionPossible Errors and Handling Errors>> Experimental conditions not fully implementedThe 3 neck-RB flask, condenser, chiller, rubber tube, and all the other apparatus connected were assumed to be a closed system. However, there was a possibility that external substances could enter the flask and make an error in measuring the boiling point and pressure.In addition, in the case of the Clausius-Clapeyron equation, it was premised that the gas generated during the evaporation process is an ideal gas. However, since the gas generated in the experiment was real gas, the experimental value obtained through the Clausius-Clapeyron equation may be subject to errors with respect to the actual value.

공학/기술| 2022.07.07| 7페이지| 2,000원| 조회(195)

성균관대학교, 성균관대, 결과레포트, 물리화학기초실험, 순수 액체의 증기압 측정

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어는점 내림 결과 레포트 A+

Basic Experiments in Physical Chemistry2021-1Sungkyunkwan UniversitySchool of Chemical EngineeringResultsTemperature(°C)Time(s)CyclohexaneSolutionASolutionB209.709.709.70409.409.409.40609.209.109.10809.008.708.901008.808.508.601208.508.308.401408.308.108.201608.107.907.901807.907.707.702007.707.507.502207.507.207.302407.407.007.202607.206.907.002807.106.706.803006.906.506.703206.806.406.503406.706.306.503606.706.106.303806.805.906.204006.805.806.104206.805.605.904406.805.405.804606.805.205.704806.804.905.605006.804.705.405206.804.505.305406.804.205.205606.803.805.105806.803.505.106006.803.505.206206.803.205.206406.803.105.306606.802.905.406806.802.805.407006.802.805.407206.802.605.407406.802.505.407606.802.505.407806.802.405.408006.802.305.308206.802.105.308406.802.105.208606.802.005.208806.801.905.109006.801.905.109206.801.805.109406.801.705.009606.801.605.009806.801.504.9010006.801.404.9010206.701.304.9010406.701.304.8010606.701.204.8010806.701.204.7011006.701.24.7011206.701.204.7011as following. (Using Table 2)(2) Solution A = = 0.68m = 0.68mol/kg(3) Solution B = = 0.25m = 0.25mol/kgCalculate the volume of soluteMolar mass(g/mol)Density(g/mL)Cyclohexane84.160.996Naphthalene(Solid)128.171.14Table3: Indicating the molar mass and density of both cyclohexane 3 and naphthalene 4.In order to calculate the volume of the naphthalene in the solution, set (mL) as the volume of the naphthalene in the solution. Then molality can be expressed as following. (Using Table3)(4)(Where , means density(g/mL) of the naphthalene and cyclohexane in Table3)From the equations (2) and (4), the volume of the naphthalene in solution A can be obtained by the following process.Solution A = 0.68 mol/kg =(5) 6.8 – 0.68x = 8.89x, x = 0.71 (mL)In the same way, the volume of the naphthalene in solution B can be obtained by the following process using equations (3) and (4).Solution B = 0.25mol/kg =(6) 2.5 – 0.25 x = 8.89x’,x’ = 0.27 (mL)3) Calculate the concentration of the naphthalene solutionUsin, according to Table 2, it deviates from the aforementioned tendency. It can be understood that the error has occurred in this part.The factors that cause the errorWhen measuring the volume of a solution with measuring cylinder, errors may occur because the volume is estimated by a glance.In addition, errors may occur as a small amount of solution may remain in the cylinder during the process of transferring the solution from the cylinder to the test tube.There is a possibility that errors may occur in the process of measuring the freezing point temperature in the part where the solution should be visually confirmed to freeze. More specifically, the solution should be stirred with a steel stirrer to prevent supercoiling, but if this part is omitted or not properly performed during the experiment, it may not be confirmed that the solution freezes even if the temperature of the solution drops below the freezing point.Plus, errors may occur due to the external temperature or pressure conde solvent and solutions.: Described in Figure 1.Determine freezing point of pure cyclohexane and solutions by using extrapolation. (Round off the calculated value to fourth decimal places when using extrapolation.)Cyclohexane: Since the heat capacity is different before and after the phase change, the temperature change value over time before and after the phase change is different. Therefore, extrapolation is performed by dividing the section based on the point where the temperature change value changes rapidly over time by using log scale graph.Figure2: Log scale of temperature (Cyclohexane) over timeAccording to Figure2, set boundary as t= 340sec, and 2 trend lines are created.The intersection of the 2 trend lines is x=15.4674, y=6.8483, so the freezing point of the cyclohexane is 6.8483oC.Solution AFigure3: Log scale of temperature (Solution A) over timeAccording to the Figure3, set boundary as t =1080sec, then 2 trend lines are created.The intersection of the 2 trend lines is x=40riment better and logistically smootherUse better apparatus such as burette instead of cylinder.ConclusionIn this experiment, the molar concentration was obtained using freezing point depression, and by using the empirical formula (equation (1)) the concentration of the solutions could be obtained. Through this experiment, we get to know that the concentration of a specific solution can be determined by measuring the freezing point depression. Although the experimental results do not follow the tendency, we can also get to know that when the molar concentration goes up, the degree of the freezing point depression also gets bigger from the empirical formula (equation (1)).References1 Atkins, P. and de Paula, J. (2014) Atkins’ Physical Chemistry. 10th Edition, Oxford University Press, Oxford. S, p1972 https://www.scienceall.com/%EC%96%B4%EB%8A%94%EC%A0%90-%EB%82%B4%EB%A6%BC-%EC%83%81%EC%88%98cryoscopic-constant/3 Hyperlink "https://ko.wikipedia.org/wiki/%EC%82%AC%EC%9D%B4%ED%81%B4%EB%A1%

공학/기술| 2022.07.07| 11페이지| 2,000원| 조회(137)

성균관대학교, 어는점 내림, 성균관대, 결과레포트, 물리화학기초실험

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순수 액체의 증기압 측정 예비레포트 A+

1.Title and ObjectiveTitle: Vapor Pressure of a Pure LiquidObjective: Understanding Clausius-Clapeyron equation and distinguishing liquids through specific temperature/pressure conditions where phase change of pure liquid occurs.2.Theoretical Backgrounds2-1) BoilingIt is a phenomenon in which a liquid changes into a gas as bubbles are generated from both the surface and the inside. In other words, it refers to a phenomenon in which vaporization occurs on the surface and inside of a liquid. In general, the temperature at which vaporization occurs inside the liquid under constant pressure is called the boiling point, and the higher the pressure, the higher the boiling point. 1

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성균관대학교, 성균관대, 예비레포트, 물리화학기초실험, 순수 액체의 증기압 측정

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화학 반응의 온도 의존성 결과 레포트 A+

Basic Experiments in Physical Chemistry2021-1Sungkyunkwan UniversitySchool of Chemical EngineeringResults5mM7mM9mM11mM13mM15mM11.3981.5011.6191.3351.7551.57721.3621.4581.7561.7311.8842.02531.3251.5061.8092.0731.8302.085Average1.3616671.4883331.7281.7131.8231.895667Table1: Absorbance value of the standard solutions for each temperatureAccording to the Beer’s law, holds (d=1cm). Therefore, the slope of the A-c graph would be extinction coefficient value(.Extinction coefficient value = 0.0523 L/cmmmolFigure1: Absorbance-concentration graph.26oC5min10min15min20min25min30min11.8831.7151.6131.5311.5231.35721.8731.7121.6081.5631.4961.40131.9031.7431.5981.5241.4951.408Average1.8863331.7233331.6063331.5393331.5046671.38866730oC5min10min15min20min25min30min11.7911.6541.6191.5571.4421.19821.8151.6681.5631.2981.3701.18931.7981.6541.4961.4621.4441.190Average1.8013331.6586671.5593331.4391.4186671.19233335oC5min10min15min20min25min30min11.8031.6671.5431.4761.3171.19321.7951.6451.5351.4461.3171.18831..98361251.4186670.052327.12556200-1.99784301.1923330.052322.79795200-2.17165Table4: Absorbance, extinction coefficient, and other values at 300CTime (min)Average absorbanceExtinction Coefficient[H2O2]t (mM)[H2O2]0(mM)51.8080.052334.56979200-1.75534101.6256670.052331.0835200-1.86164151.5446670.052329.53474200-1.91275201.4636670.052327.98598200-1.96661251.3133330.052325.11153200-2.07499301.1896670.052322.74698200-2.17389Table5: Absorbance, extinction coefficient, and other values at 350CTime (min)Average absorbanceExtinction Coefficient[H2O2]t (mM)[H2O2]0(mM)51.6496670.052331.54239200-1.84699101.250.052323.90057200-2.12441151.2996670.052324.85023200-2.08545201.1506670.052322.00128200-2.20722251.0290.052319.67495200-2.31897300.8160.052315.60229200-2.5509Table6: Absorbance, extinction coefficient, and other values at 410CSince fenton reaction is 1st order reaction, the following equation holds.= -kt (k = rate constant)Therefore the absolute value of slope of the – t graph would be rate concted the measured value and consequently caused an error. In order to reduce this error, it is necessary to check whether bubbles occur when the solution is filled into the 96-well plate through micropipette.>> Measuring temperature of the mixed solutions.The heating device maintained the temperature at which the reaction occurred, however it could be changed by external factors such as heat and material entry. Therefore, there is a limitation in that the temperature at which the reaction occurs cannot be accurately set. And this would have caused an error in the process of calculating the rate constant. To reduce such an error, a closed heating device that can block external factors should be used in the experiment.>> Measuring time after mixing the solutions.After mixing the solution, the time was measured using a timer. The experiment was carried out by resetting the 5-minute timer and starting again. In this process, there is a possibility that the reaction time may have been longer collision (an elementary reaction) between molecules A and B. The collision angle, the relative translational energy, the internal (particularly vibrational) energy will all determine the chance that the collision will produce a product molecule AB. Macroscopic measurements of E and k are the result of many individual collisions with differing collision parameters. To probe reaction rates at molecular level, experiments are conducted under near-collisional conditions and this subject is often called molecular reaction dynamics.1Another situation where the explanation of the Arrhenius equation parameters fall short is in heterogeneous catalysis Hyperlink "https://en.wikipedia.org/wiki/Heterogeneous_catalysis" o "Heterogeneous catalysis" , especially for reactions that show Langmuir-Hinshelwood kinetics. Clearly, molecules on surfaces do not "collide" directly, and a simple molecular cross-section does not apply here. Instead, the pre-exponential factor reflects the travel across the quation, and n satisfies -1 Present the integrate rate law of 2nd order reaction 4Half-life (t1/2) in reaction can be obtained through the above equation.>> Plugging t = t1/2>> Organizing the equation with respect toConclusionIn this experiment, reactions under different temperature conditions were examined to check the temperature dependence of chemical reactions. First, in order to measure the extinction coefficient, the absorbance of the standard solution was measured. According to Beer's Law, the extinction coefficient value (slope of the trend line) was induced by measured concentration of the solution and the absorbance values. Using the obtained extinction coefficient, Beer's Law was once again taken to obtain [H2O2]t, which is a concentration value of H2O2 over time. Since the Fenton reaction is 1st order reaction, = -kt holds. Through this equation, rate constant (absolute value of the slope of the trend line) was induced by plotting and t values. Meanwhile, Arrhenius equation/832

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성균관대학교, 성균관대, 결과레포트, 화학 반응의 온도 의존성, 물리화학기초실험

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어는점 내림 예비 레포트 A+

Basic Experiments in Physical Chemistry2021-1Sungkyunkwan UniversitySchool of Chemical EngineeringTitle and ObjectiveTitle: Freezing Point DepressionObjective: Figure out concentration of naphthalene solution in cyclohexane using freezing point.Theoretical Backgrounds2-1) Boiling Point ElevationFigure1. Equilibrium between A in the pure vapour and A in the mixture at 1 atm. 1Equation (3) can be rearranged as follows.(Using Gibbs-Helmholtz equation)(Differentiate both sides with respect to temperature, T)(Multiply both sides with dT, then integrate)(Where is the mole fraction of solute)(Where )Since it also follows that,(4)Then the equation (4) can be rearranged into the following equations.(5) , (6) K = (Where K means molarity)From the equation (5), it is true that the degree to which the boiling point goes up is proportional to the molarity.2-2) Freezing Point DepressionFigure 2. Equilibrium between A in the pure solid and A in the mixture at 1 atm. 2The equation (7) can be rearranged as following.(8) , (9) K’ = (Where is the freezing point depression)Especially in the case when the solution is dilute, the mole fraction is proportional to the molarity of the solute, b, and it’s common to write the equation (8) as following. 3(10) (Where is the empirical freezing-point constant)From the equation (10), it is true that the degree to which the freezing point goes down is proportional to the molarity.2-3) SupercoolingIt refers to a phenomenon in which phase transition is not visible when cooling the material even after passing the transition temperature. For example, in the process of rapidly cooling the temperature of the substance, even though the temperature is below the solidifying point, it still remains liquid. Since such state is very unstable, change to a solid can easily occur by an external impact. 4Experiment3-1) Apparatus & Reagents (MSDS)Thermometer For measuring the temperature of solution.Rubber Stopple For combining two test tubes.Test Tube For containing cyclohexane and naphthalene solutions.Container For containing ice water.Steel stirrer For maintaining the temperature of the solution even and preventing supercoiling of the solutions.Stop watch For measuring the time.// Both Cyclohexane and Naphthalene are flammable and toxic.3-2) ProceduresDetermine the freezing point of cyclohexaneMix water and ice in the container to make ice water.Insert the test tube into the rubber plug, and then place the combined rubber plug and test tube into the container.Place 10 ml of cyclohexane into a small test tube using a mass cylinder.Put a small test tube into a large test tube in a container.Insert the thermometer into a small test tube.// Make sure the end of the thermometer to contact cyclohexane solution.// Use two steel stirrers to let the temperature of ice water and of the solution be the same until the end of the experiment.Turn on the thermometer and wait until the temperature of cyclohexane reaches 10 degrees.// If you want to lower the temperature faster, add sodium chloride to the ice water.Record the temperature of cyclohexane for 20 minutes every 20 seconds.// Stir continuously through the steel stirrer while measuring.Determine the freezing temperature of cyclohexane solution with varying concentrationThe same process in A is performed through different concentrations of naphthalene aqueous solutions.// Before conducting the experiment, naphthalene must be completely dissolved in an aqueous solution.// The temperature rises at a specific point Overcooling and latent heat increases the temperature of the aqueous solution.Answers for Pre-Lab ReportRead Atkins 5.5 and summarize the related principles including the meaning of colligative property and freezing point depression.:Why is the freezing point of a solution of a nonvolatile solute less than that of the pure solvent?: Because the chemical potential of the solvent in the mixture is lower than that of the pure solvent.Explain super cooling: Referred in the 2. Theoretical BackgroundsPrepare data sheet to record your data in the lab. This will used in the report.T1T2…T30TfreezingconcentrationAB// Tfreezing means the temperature of the cyclohexane solution at which it freezes.// = 6.5oC - Tfreezing (Where 6.5oC is the freezing point of pure cyclohexane)// T1, T2, … , T30 mean the temperature of the solution measured every 20 seconds for 20 minutes.ReferencesAtkins, P. and de Paula, J. (2014) Atkins’ Physical Chemistry. 10th Edition, Oxford University Press, Oxford. S, p196-197Atkins, P. and de Paula, J. (2014) Atkins’ Physical Chemistry. 10th Edition, Oxford University Press, Oxford. S, p197Atkins, P. and de Paula, J. (2014) Atkins’ Physical Chemistry. 10th Edition, Oxford University Press, Oxford. S, p197Scienceall.com- Hyperlink "https://www.scienceall.com/%EA%B3%BC%EB%83%89%EA%B0%81supercooling-%E9%81%8E%E5%86%B7%E5%8D%B4/" https://www.scienceall.com/%EA%B3%BC%EB%83%89%EA%B0%81supercooling-%E9%81%8E%E5%86%B7%E5%8D%B4/

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성균관대학교, 어는점 내림, 성균관대, 예비레포트, 물리화학기초실험

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