Determination of the Rate Law and Activation Energy for the Dissociation of Ferroin
Kim, Taewoo, Trey L Arnold, Kyle A Leland, Aimee M Morey, Department of Chemistry, USAF Academy, CO 80840
ABSTRACT
Blue wavelength was used to measure absorbance; using initial data and Beer’s law, calculated molar extinction coefficient was 10953 L∙mol^(-1)∙cm^(-1). Variations of concentration over time were graphed to figure out dissociation of ferroin being first-order reaction and sulfuric acid being zero-order. Thus, under the rate law, the solution’s rate was found to be k〖[Ferroin]〗^1 〖[Sulfuric acid]〗^0, where rate constant k = 9.12x〖10〗^(-4) s^(-1). Half-life was 759.87 sec and Ea (activation energy) was 56.82 KJ.
INTRODUCTION
Chemical kinetics, also
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Use blue LED color for maximum absorbance of Ferroin and scroll down the colorimeter screen to view absorbance at your chosen wavelength. Measure the initial absorbance of the mixture with colorimeter, record it and use this information to determine the molar extinction coefficient for Ferroin. Place the cuvette into 40°C water bath and let it heat up. Remove cuvette from water bath to measure the absorbance of mixture with two minutes of interval in between, putting the cuvette immediately back after the measurement. Be sure to dry the cuvette (ex. with paper towel) before putting into colorimeter. Continue until the absorbance drops below 0.2 or when you have the 10th measurement. For second experiment, repeat procedure using 0.20M sulfuric acid by diluting 0.40M sulfuric acid. For the last experiment, use 0.40M sulfuric acid again but put into 45°C water bath instead of …show more content…
ε should be all same for three experiments so error occurred here. Source of this error might be little water or moisture inside colorimeter before starting new experiment. This could affect absorbance of wavelength by colorimeter. Also, I used 45°C graph to determine the order of ferroin because when I plotted all three graphs for 40°C, zero-order graph had higher percentage of R^2, than first-order graph. It must have been human mistake as my lab partner forgot to measure for every 120 seconds but randomly recorded four points instead. (120, 240, 430, 540)
Therefore, rate constant is little higher than it is supposed to be. At 40 °C, k would be -6.47 x〖10〗^(-4) s^(-1) and half-time would be 1071 seconds. It is same for activation energy. I think it is less than it should be because of human mistake while taking the measurement. I am guessing it might be around 100KJ based on references.
REFERENCE
John O. Edwards; Kathleen Edwards; Jorge Palma; The reactions of ferroin complexes. A color-to-colorless freshman kinetic experiment 1975, 52, 408 Simeen Sattar; Unified Kinetics and Equilibrium Experiment: Rate Law, Activation Energy, and Equilibrium Constant for the Dissociation of Ferroin 2011, 88, 457-460 T. S. Lee; I. M. Kolthoff; D. L. Leussing; Reaction of Ferrous and Ferric Iron with 1,10-Phenanthroline. I. Dissociation Constants of Ferrous and Ferric Phenanthroline
2. Cooper, M. M., Cooperative Chemistry Laboratory Manual, McGraw-Hill: New York, NY, 2009, p. 60.
barbier reaction: In a 50 mL round bottom flask that had a reflux condenser attachment, saturated ammonium chloride (5 mL), THF (1 mL), zinc powder (0.4 g), benzaldehyde (0.500 mL, 0.5225 g, 4.92 mmol), and allyl bromide (0.470 mL, 0.6533 g, 5.40 mmol) were charged with stir bar and stirred at room temperature for 45 minutes. Diethyl ether (10 mL) was added to the reaction mixture and stirred. The mixture was gravity filtered into a beaker that was topped with a watchglass. The filtrate was transferred to a separatory funnel and the organic layer was extracted with deionized water (10 mL) and diethyl ether (15 mL). The organic layer was placed into an Erlenmeyer flask and the aqueous layer was placed into a beaker, which was extracted with
The analyzed yellow#5 wavelength was determined to 395nm because the actual wavelength 427nm was restricted in the Micro lab. The R2 value of the graph is 0.9827, and the level of data accuracy it indicated extremely weak data correlation. The first one dilution data points excluded from the standard curve because the point is not in the linear curve. The first concentration and absorbance value are the highest point in the graph that cannot connect as linear with another data point. After removing the first data point, the standard curve is clear and make
Felder, M. Richard, Elementary Principles of Chemical Processes, 3rd ed.; Wiley: New Jersey, 2000; p 631.
A spectrum is a group of light wavelengths that are ordered in relation to their wavelength length. The electromagnetic spectrum consists radio waves, microwaves, infrared, visible, ultraviolet, X-rays and gamma rays. (1)Specifically, this lab looks at the visible light part of the spectrum because one of the colors in the visible light spectrum is shine through the sample. The visible light spectrum consists of colors of red, orange, yellow, green, blue, indigo, and violet. The color chosen to be shine through the sample is affected by the color of sample when mixed with the indicator Ammonium Vanadomolybdate (AMV). The color on the color wheel that is opposite of the solution’s color is the color that is shined through the
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...Coauthor, ChemBioChem 2006, 7, 1-10; b) A. Author, B. Coauthor, Angew. Chem. 2006, 118, 1-5; Angew. Chem. Int. Ed. 2006, 45, 1-5.))
0,74 0,87 1,00 0,49 100... ... middle of paper ... ... some groups had got different leakage of the pigment in the test tubes with water.
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The purpose of this experiment is to use our knowledge from previous experiments to determine the theoretical, actual, and percent yields of the lead chromate from the reaction of solutions of potassium chromate and lead nitrate (Lab Guide pg. 83).
This question refers to the example data given below. Using the rate law and the experimental values given below, calculate k.
To examine the interaction between two molecules in solution without isolating the compound Jobfs method is used. Although unstable compounds tend to be generated, this is not a reflection of weak interactions. In some cases, the transition metal species cannot be crystallized from the solution and separated from the other species present. Without Jobfs Method this composition can be very difficult to deduce.
The Results obtained from the experiment proved the original theory at the start of the experiment. The results table clearly shows pigment levels increasing with the rinsing temperature increments.
... point was subjective; however it would have been a systematic error because I consistently judged the end point of my experiment. To eliminate this inaccuracy I should have used a colorimeter to judge the end point of my experiment.
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