Re-formate the objective, methods, and the experimental design?

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i just want to "Re-formate" the objective, methods and the experimental design.. I highlighted them in yellow highlight.

I want to Re-foramte them, because I took this course last semester and I repeated it again this semester for better grade. the experiment is similar to the last semester, but the teacher wants me to Re-formate them in different words or or grammar or sentences so they don't look similar.. just do the best you can :)

Measuring the Diffusivity of Acetone and Ethanol in Air at 40 and 50 Degrees Celsius with Winkelmann’s Method Introduction Background Diffusion refers to the process by which molecules move from a higher concentration to a lower concentration through a gradient, without the use of energy, until equilibrium is attained (“Diffusion and Osmosis”). Diffusion is the outcome of random molecular motion. When the temperatures are high, molecules move quicker this makes diffusion occur more rapidly. The behavior of diffusion does not rely on chemical reactions. As long as there is a presence of a concentration gradient, diffusion will happen. An experiment will be conducted to show the vapor diffusivity of acetone and ethanol into air. During the experiment unimolecular diffusion will be sustained without the occurrence of a chemical reaction. By monitoring the rate of loss of the liquid phase, the Stephen-Winkelmann method is applied to determine the rate of mass flux into the gas phase. Temperatures of specific systems directly affect transport properties such as velocity, diffusion, and thermal conductivity. To perceive the separation of procedures such as distillation and chemical reactor design, the concept of molecular diffusion has to be used. Molecular diffusion has many educational applications as well. Molecular diffusion is commonly used in various areas such as; chemistry, physics, biology, and engineering. One main example of molecular diffusion is osmosis; this is a process seen throughout nature in many biological processes. Diffusion is very important to understand because it is encountered in every human’s lifetime (Whitmer). Objective The purpose of this lab was to determine the diffusivities of acetone and ethanol by measuring the rate at which the liquid level of both compounds dropped in a capillary tube at 40 ℃ and 50 ℃. The experimental value of acetone’s diffusivity at 50 ℃ was calculated using equations derived from Fick’s Law and was statistically compared to acetone’s experimental diffusivity at 40 ℃, ethanol’s experimental diffusivity at 50 ℃, a value found in literature, and a value calculated through mass transfer equations. 1 Theory Diffusivity of acetone was calculated with Winkelmann’s method by measuring the time it takes for a liquid in a tube to lower a certain distance. The liquid acetone evaporated out of a narrow diameter glass tube at constant temperature and pressure while air flowed over the top of the tube. The diffusivity of acetone was calculated with: 𝐷𝐴𝐵 = 𝜌𝐴 ∗(𝑧𝐹2 −𝑧02 )∗𝑅∗𝑇∗𝑝𝐵𝑀 2∗𝑀𝐴 ∗𝑡𝐹 ∗𝑃∗(𝑝𝐴1 −𝑝𝐴2 ) (eq. 1) where 𝜌𝐴 is the density of acetone, 𝑧𝐹 is the final height of the liquid, 𝑧0 is the initial height of the liquid, R is the ideal gas constant, T is absolute temperature, 𝑃𝐵𝑀 is given by equation 2, 𝑀𝐴 is the molar mass of acetone, 𝑡𝐹 is the time it took the liquid to move from 𝑧0 to 𝑧𝐹 , P is the atmospheric pressure, 𝑝𝐴1 is the partial pressure of acetone above the liquid acetone, and 𝑝𝐴2 is the partial pressure of acetone at the top of the tube. The value of 𝑝𝐴2 can be assumed to be zero since the airflow over the top will keep the vapor pressure of acetone very low at the top of the tube. The quantity 𝑝𝐵𝑀 was calculated with: 𝑝𝐵𝑀 = 𝑝𝐴1 −𝑝𝐴2 (𝑃−𝑝𝐴2 ) ] (𝑃−𝑝𝐴1 ) 𝑙𝑛[ (eq. 2) where 𝑝𝐴1 is the partial pressure of acetone above the liquid acetone, and 𝑝𝐴2 is the partial pressure of acetone at the top of the tube. The partial pressure of acetone was calculated directly above the liquid in units of bar with Antoine’s equation: 𝐵 𝑝𝐴1 = 10(𝐴−𝐶+𝑇) (eq. 3) where A, B, and C are constants equal to 4.42448, 1312.253, and -32.445 respectively and T is temperature in Kelvin (Ambrose, 1974). Antoine’s equation was also used for ethanol with the constants A, B, and C equaling 4.92531, 1432.526, and -61.819 respectively (Ambrose, 1975). The diffusivity was also calculated computationally with: 𝐷𝐴𝐵 = 1/2 1 1 + ) 𝑀𝐴 𝑀𝐵 2 1/3 𝑃[(∑ 𝑣𝐴 ) +(∑ 𝑣𝐵 )1/3] 1.00𝑥10−1 𝑇 1.75 ( (eq. 4) where T is absolute temperature, Ma is molar mass of acetone, MB is molar mass of air, P is absolute pressure in bar, ∑ 𝑣𝐴 is the sum of the diffusion volume for acetone, and ∑ 𝑣𝐵 is the sum of the diffusion volume for air (Fogler). 2 Methods Apparatus In this study, the Armfield Gaseous Diffusion Coefficient Apparatus was used to perform the vapor diffusion experiment according to Winkelmann’s method. The apparatus pictured in Figure 1 utilized a glass capillary tube to contain the liquid species being tested. A heating block held the capillary tube and maintained the liquid at a constant temperature, which was set using the digital display. A fan provided a steady flow of air into the apparatus and a flexible tube to the top of the capillary tube carried this air. The airflow was used to maintain the partial pressure of the liquid species at zero at the top of the capillary tube. A camera was used to take images of the level of the liquid contained in the capillary tube. The readings of the liquid levels at the preferred temperature appeared on the digital display and a personal computer was attached to the apparatus by a USB port to capture and record these images. Figure 1: This figure represents the Armfield Gaseous Diffusion Coefficient Apparatus and the various important components that will be utilized. Experimental Design 3 In each experiment, the independent variable in the design was the time while the height from the top of the tube was the response variable. The density of the the liquid being tested, ideal gas constant, temperature, partial pressures, molar mass, and pressure were assumed constant throughout the experiments. The temperature was varied, and the type of compound was changed between acetone and ethanol. The calculated variable was the diffusivity in all the trials. For the first experiment, the diffusivity of acetone was measured at a temperature of 50 °C. This experiment with acetone at 50 °C was repeated for a total of three times. For the second experiment, the diffusivity of acetone was measured at 40 °C once. In the third experiment, acetone was substituted for ethanol, the temperature was kept at 50 °C, and the diffusivity of ethanol at 50 °C was measured once. Method of Analysis For each time interval, the height and time values for acetone and ethanol were input into equation 1 to determine the diffusivity at the successive time points. The diffusivity values of acetone were compared, using two separate unequal variance t-tests, to a diffusivity value found in literature and a diffusivity value calculated using equation 4. It was determined, using the t-tests, if there was a statistically significant difference between the measured diffusivities and those found in literature. Likewise, it was determined if there was a statistically significant difference between the measured diffusivities and those that were calculated using equation 4. The diffusivity values of acetone for the tests at 40 ℃ and 50 ℃ were compared to one another using equal variance t-tests to determine if there was a statistically significant difference between the data. Another equal variance t-test was used to determine if there was a statistically significant difference between the diffusivity of acetone and the diffusivity of ethanol at 50 ℃. A plot was made of the height of liquid acetone vs time for the 40 ℃ and 50 ℃ tests. This plot displayed time on the x-axis and (𝑧𝐹2 − 𝑧02 ) ∗ 𝐶 on the y-axis where 𝐶 = 𝜌𝐴 ∗𝑅∗𝑇∗𝑝𝐵𝑀 . 2∗𝑀𝐴 ∗𝑃∗(𝑝𝐴1 −𝑝𝐴2 ) A least squares regression was fit to the data. From rearranging equation 1, the slope of the regression corresponds to the experimental 𝐷𝐴𝐵 value. Safety Safety glasses are very important objects to be used in the lab. They should be worn as soon as one enters the lab. Acetone is a very flammable substance, the use of gloves is advised when handling acetone and capillarity tubes. Also, it is advised not to touch the apparatus with bare hands in order to avoid burns; this is because surfaces might be hot on the apparatus. Extreme care should be taken when 4 handling glass capillary tubes because the tubes are very delicate and difficult to replace. It is important to lubricate capillary tube with silicone before inserting the tube into rubber gland; this will help the tube to slide in smoothly. It is advised to use temperatures below 60 °C as a set point, so the equipment being used is not damaged. To avoid the acetone from boiling, it is important to set the temperature controller no higher than 50 °C (Wettstein). Anticipated Results Table 1: A table of the various T-tests performed against the experimental acetone at 50 °C and the corresponding P-values. P-value at 95% Confidence Interval Unequal Variance T-Test: Experimental Diffusivity Acetone at 50 2.6 ∗ 10−12 °C versus Calculated Diffusivity Unequal Variance T-Test: Experimental Diffusivity Acetone at 50 0.052 °C versus Diffusivity of Acetone in Literature at 50 °C Equal Variance T-Test: Experimental Diffusivity Acetone at 50 °C 0.31 versus Experimental Diffusivity Acetone at 40 °C Equal Variance T-Test: Experimental Diffusivity Acetone at 50 °C 0.017 versus Experimental Diffusivity Ethanol at 50 °C Two unequal variance T-tests were performed comparing the experimental diffusivity data of acetone at 50 °C against the calculated diffusivity and a diffusivity value found in literature. The Pvalues, which are all listed in Table 1, were 2.6 ∗ 10−12 and 0.052 respectively, so the experimental diffusivity of acetone was found to be statistically different at the 95% confidence level than the calculated diffusivity. In contrast, the experimental diffusivity and value found in literature were not found to be statistically different at the 95% confidence level. An equal variance T-test was performed on the experimental diffusivity of acetone at 50 °C against the experimental diffusivity of acetone at 40 °C, and a P-value of 0.31 was obtained. The P-value was greater than 0.05, so the data was not statistically different at the 95% confidence level. Another equal variance T-test was performed on the experimental diffusivity of acetone at 50 °C and the 5 experimental diffusivity data of ethanol at 50 °C. The P-value was 0.017 between acetone and ethanol at 50 °C, so the data was statistically different at the 95% confidence level. A regression analysis was performed in Figure 2 that returned a value of 10.06 for the slope, which corresponds with the diffusivity in millimeters squared per second. The slope is within one standard deviation of the mean, 10.28, for the experimental data. The R2 value was also 0.999, so Figure 2 shows a strong linear relationship between time and the distance down the tube squared. Distance from Top of Tube Squared times C (mm2 *(min/s)) 2000 y = 10.056x R² = 0.99888 1600 1200 800 400 0 0.00 50.00 100.00 150.00 200.00 Time (min) Figure 2: The liquid level in the tube is from the top of the tube squared against the time it took for the level to drop. 6 References Ambrose, D.; Sprake, C.H.S.; Townsend, R., Thermodynamic properties of organic oxygen compounds XXXIII. The vapour pressure of acetone, The Journal of Chemical Thermodynamics, 1974, 6, 7, 693-700. Ambrose, D.; Sprake, C.H.S.; Townsend, R., Thermodynamic Properties of Organic Oxygen Compounds. XXXVII. Vapour Pressures of Methanol, Ethanol, Pentan-1-ol, and Octan-1-ol from the Normal Boiling Temperature to the Critical Temperature, J. Chem. Thermodyn., 1975, 7, 2, 185-190. The College Board. “Diffusion and Osmosis.” Cellular Processes: Energy and Communication, media.collegeboard.com /digitalServices/pdf/ap/bio-manual/Bio_Lab4-DiffusionandOsmosis.pd. Fogler, and Gurmen. “Prediction of Binary Gas Diffusivities.” Chapter 11, www.umich.edu/~elements/fogler&gurmen/html/course/lectures/eleven/exam4.htm. Accessed 25 Sept. 2017 Wettstein, Stephanie, Dr. Gas Diffusion Apparatus. N.d. Description of Procedure For ECHM 442 Vapor Diffusivity Experiment. Whitmer, Phil. “Why Is Diffusion Important to the Life of a Cell?” Sciencing, 24 Apr. 2017, sciencing.com/diffusion-important-life-cell-8759126.html. (intro 2) 7 Appendix Table A1: Statistical Analysis for t-test assuming Unequal Variances for acetone diffusivity at 50 °C versus calculated diffusivity Variable 1 Variable 2 Mean 10.28200296 12.1883 Variance 1.789583583 0 45 2 Observations Hypothesized Mean Difference df t Stat 0 44 -9.559184329 P(T<=t) one-tail 1.31684E-12 t Critical one-tail 1.680229977 P(T<=t) two-tail 2.63367E-12 t Critical two-tail 2.015367574 Table A2: Statistical Analysis for t-test assuming Unequal Variances for acetone diffusivity at 50 °C versus diffusivity in Literature Variable 1 Variable 2 Mean 10.28200296 10.68 Variance 1.789583583 0 45 2 Observations Hypothesized Mean Difference df t Stat 0 44 -1.995768217 P(T<=t) one-tail 0.02608623 t Critical one-tail 1.680229977 P(T<=t) two-tail 0.05217246 t Critical two-tail 2.015367574 8 Table A3: Statistical Analysis for t-test assuming Equal Variances for acetone diffusivity at 50 °C versus acetone diffusivity at 40 °C Variable 1 Variable 2 Mean 10.28200296 9.955009074 Variance 1.789583583 2.856109236 45 45 Observations Pooled Variance 2.32284641 Hypothesized Mean Difference df 0 88 t Stat 1.017702047 P(T<=t) one-tail 0.155804711 t Critical one-tail 1.662354029 P(T<=t) two-tail 0.311609421 t Critical two-tail 1.987289865 Table A4: Statistical Analysis for t-test assuming Equal Variances for acetone diffusivity at 50 °C versus ethanol diffusivity at 50 °C Variable 1 Variable 2 Mean 10.28200296 11.36352162 Variance 1.789583583 7.135198177 45 45 Observations Pooled Variance Hypothesized Mean Difference df t Stat 4.46239088 0 88 -2.428518792 P(T<=t) one-tail 0.008597721 t Critical one-tail 1.662354029 P(T<=t) two-tail 0.017195441 t Critical two-tail 1.987289865 9 Table A5: Blank Data Sheet for acetone at 40 °C 40 °C Acetone Time Height Z0 Height Zf Time Height Z0 Height Zf Acetone (min) Acetone (mm) Acetone (mm) (min) Acetone (mm) (mm) 4 96 8 100 12 104 16 108 20 112 24 116 28 120 32 124 36 128 40 132 44 136 48 140 52 144 56 148 60 152 64 156 68 160 72 164 76 168 80 172 84 176 88 180 92 10 Table A6: Blank Data Sheet for acetone at 50 °C 50 °C Acetone Time Height Z0 Height Zf Time Height Z0 Height Zf Acetone (min) Acetone (mm) Acetone (mm) (min) Acetone (mm) (mm) 4 96 8 100 12 104 16 108 20 112 24 116 28 120 32 124 36 128 40 132 44 136 48 140 52 144 56 148 60 152 64 156 68 160 72 164 76 168 80 172 84 176 88 180 92 11 Table A7: Blank Data Sheet for ethanol at 50 °C 50 °C Ethanol Time Height Z0 Height Zf Time Height Z0 Height Zf Acetone (min) Acetone (mm) Acetone (mm) (min) Acetone (mm) (mm) 4 96 8 100 12 104 16 108 20 112 24 116 28 120 32 124 36 128 40 132 44 136 48 140 52 144 56 148 60 152 64 156 68 160 72 164 76 168 80 172 84 176 88 180 92 12 Sample Calculations: 𝜌 ∗(𝑧𝐹2 −𝑧02 )∗𝑅∗𝑇∗𝑝𝐵𝑀 (784 𝑘𝑔/𝑚3 )∗(322 𝑚𝑚2 −02 )∗(8.314 𝐽/𝑚𝑜𝑙/𝐾)∗(323 𝐾)∗(50112 𝑃𝑎) = = 2∗(0.05808 𝑘𝑔/𝑚𝑜𝑙)∗(10800 𝑠)∗(101000 𝑃𝑎)∗(80900 𝑃𝑎) 𝐴 ∗𝑡𝐹 ∗𝑃∗(𝑝𝐴1 −𝑝𝐴2 ) 𝐴 Equation 1: 𝐷𝐴𝐵 = 2∗𝑀 𝑚𝑚2 𝑠 10.54 Equation 2: 𝑝𝐵𝑀 = 𝑝𝐴1 −𝑝𝐴2 (𝑃−𝑝𝐴2 ) ] (𝑃−𝑝𝐴1 ) 𝑙𝑛[ Equation 3: 𝑝𝐴1 = 10 (𝐴− 𝐵 ) 𝐶+𝑇 = 80900 𝑙𝑛[ = 50112 Pa (101000)) ] (101000−80900) =10 1312.253 ) −32.445+323 (4.42448− 1 1 + )1/2 58 𝑔/𝑚𝑜𝑙 28.97 𝑔/𝑚𝑜𝑙 (1 𝑏𝑎𝑟)[(66.86)1/3 +(20.1)1/3 ]2 1 1 + )1/2 𝑀𝐴 𝑀𝐵 𝑣𝐴 )1/3 +(∑ 𝑣𝐵 )1/3 ]2 1.00𝑥10−1 𝑇 1.75 ( Equation 4: Calculated diffusivity value, 𝐷𝐴𝐵 = 1.00𝑥10−1 (323𝐾)1.75 ( = 0.809 bar 𝑃[(∑ = 𝑚𝑚2 𝑠 =12.19 Experimental Protocol 1. Put on closed toed shoes, long pants, and safety glasses. 2. Plug in the Armfield Gaseous Diffusion Coefficient Apparatus to turn on the unit. 3. Connect the computer to the apparatus with the USB port and start the software program, eScope. 4. Turn on the temperature moderator on the PID controller (digital display) and set the desired temperature to 50 °C by pressing the F button, using the up and down arrows to set the temperature, hitting the F button again, and waiting eight seconds. 5. Wash the capillary tube with acetone. 6. Use a hypodermic syringe to fill the capillary tube with acetone to a height of 35 mm. 7. Carefully insert the capillary tube into the apparatus through the ring at the top left of the apparatus. Add lubricant if necessary. 8. Check if the liquid level can be seen on the digital display screen and if the resolution (on the top menu bar) is set to 640x480. Adjust if necessary. 9. Carefully, connect the air tubing from the fan located on the top of the apparatus to the tube piece located above the capillary tube. 10. Check that the air is blowing across the tube. 11. On the computer, left click on the measure drop down icon and click ‘Calibration’. 13 12. Left click on the scale on the left of the image, and count down a distance of 5 mm. Left click again on the scale, and type 5 mm in the actual dimension box. Click the ok box. 13. Left click the clock image for the time lapse icon. Select the time interval between each image capture as 240 seconds. Select the total number of images as 45. 14. Left mouse click the ‘Start’ button to begin the time lapse feature. 15. Record all height changes from the image captures by double left clicking on the images on the left and then clicking the ‘measure’ icon and select ‘straight angle line’ to measure the level at the meniscus. Left click the mouse at the lowest point of the meniscus and left click at the top of the screen. Then move the text where it can be read and record the data. 16. When the liquid runs out, carefully remove the air tubing from the tube piece located above the capillary tube. 17. Carefully remove the capillary tube. 18. Save the data by clicking the floppy disc icon at the top of the screen. Name and save the file. 19. Repeat steps 4-18 two more times. 20. Set the desired temperature to 40 °C for the second experiment for acetone at 40 °C. 21. Repeat steps 5-18 for the second experiment. 22. Set the desired temperature to 50 °C for the third experiment for ethanol at 50 °C. 23. Wash the capillary tube with acetone. 24. Use a hypodermic syringe to fill ethanol in the capillary tube to a height of 35 mm. 25. Repeat steps 7-18 using ethanol as the liquid at a temperature of 50 °C. 26. Wash the capillary tube with acetone. 27. Disconnect the apparatus from the computer, close the eScope program, and unplug the Armfield Gaseous Diffusion Coefficient Apparatus. 28. Leave the lab and take off your closed toed shoes, pants, and safety glasses. 14 15

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