Lab on Complex Ion Composition Objective The objective of this experiment is to study the continuous variations method that is used to determine the composition of the solution Ni2+ ethylenediamine complexes. Background 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. Jobfs Method analyzes the value of n in the equilibrium: Z + nL ¨ZLn Varying the n value carries out the experiment. Absorbencies of each of the ZLn complexes are obtained. The sum of the concentrations of the metal, Z, and the ligand, L, are kept equal. With the ratio of the ligand to the metal in the solution with the maximum absorbance for the ZLn complex, the value of n can be determined as well as the composition of ZLn. The metal Ni2+ and the ligand ethylenediamine (en) are studied in this experiment. Solutions are prepared with varying compositions of Ni(en)n2+. Using the equilibrium constants, it is possible to identify which species is present. If the constant for the formation of a species where n is 2 is larger than a species whose constant equals 3 then the former species is pre-dominant. Jobfs Method is limited in that it will give non-integral values of the n present if a fourth complex, ZLn+1, exists. If there is a large variation between the equilibrium constants then only two complexes will be present in the prepared solutions. The absorbance values are plotted, then the value of n can be calculated. Procedure The procedure for this experiment can be found in Inorganic Chemistry Lab Manual prepared by Dr. Virgil Payne. Data and Observations 530 545 578 622 640 0.3 0.079 0.134 0.277 0.555 0.605 0.4 0.088 0.141 0.333 0.596 0.638 0.5 0.099 0.154 0.35 0.57 0.579 0.6 0.158 0.218 0.414 0.584 0.552 0.7 0.212 0.289 0.436 0.459 0.411 0.8 0.376 0.424 0.396 0.203 0.149 0.9 0.213 0.224 0.168 0.061 0.036 1 0.052 0.067 0.142 0.465 0.647 Results and Discssion 1. Ni(en)32+ Ni(en)2(H2O)22+ Ni(en)1(H2O)42+
Felder, M. Richard, Elementary Principles of Chemical Processes, 3rd ed.; Wiley: New Jersey, 2000; p 631.
The color that was chose to be shined through the sample was purple. The spectrophotometer was set at a wavelength of 400nm to represent the purple color. It was zeroed using the blank meaning the spectrophotometer read zero as absorbance amount. The blank consisted of 5mL of water and 2.5 mL AVM and it was placed in cuvette. A solution with a known concentration of 2.0x10-4 M was used in the spectrometer. For this solution, 5 mL of the solution with 2.5 mL of AMV was placed in the cuvette. The cuvette was placed inside of spectrophotometer and the amount of absorbance was recorded. This procedure that involves a solution with a known concentration was repeated for the concentrations:1.0x10-4 M,5.0x10-5 M,2.0x10-5M, and1.0x10-5M.A unknown solution absorbance was measured by putting 5 mL of unknown solution with 2.5 mL AMV in a cuvette. The cuvette was placed in the spectrophotometer and the amount of absorbance was recorded. The procedure that deals with the unknown solution was repeated 2 more times with the same solution and the same amount of solution and AMV. The average of the three unknown solution was calculated and the concentration of the unknown solution was
In this lab, lab 4.3 Comparing the Concentrations of Saturated Solutions, we set out to find and compare the solubilities of two solids in water. In addition, we tested if solubility is a characteristic property of a solid in a given liquid. This lab allowed us to test and use a reliable way to measure the solubility of a solid. This lab can be replicated for any solid with the same procedure, thus it gives us a method to calculate solubility. The two solids we tested in this experiment were NaCl (Sodium Chloride) and NaNO3 (Sodium Nitrate).
Stability of a complex in solution is known to be the separation of two compound resulting in equilibrium state, theoretically it was observed that; there greater association, the higher the stability of the
The purpose of this lab was to understand the relationship between emission spectra and atomic structure using small samples of 7 chloride salts of different metals. Emission spectra(or line spectra) is a collection of wavelengths representing different energies. Electrons in an atom occupy different energy levels and are in the ground state when they are at a low energy level. When they start to enter a higher energy level after gaining energy, they start to enter their excited state. Once in their excited state, they proceed to go back to their respective energy level by emitting light in the form of a
Before beginning the experiment observe and record the physical appearance of all the chemicals used in the experiment. First write a balanced chemical equation that has Zinc iodide as product when Barium iodide and zinc sulfate are used. To begin today’s lab, weigh a small test tube on a scale that goes to the hundredths place. Using a clean spatula add .45 g + .03 grams of zinc sulfate heptahydrate (.25 g + .03 grams if zinc sulfate is used) into the small test tube. Dissolve the sample in 2 mL of deionized water. Make sure al of the powder is mixed with the water, stopper the test tube and shake for about 1 to 1 ½ minutes to dissolve. Let the test tube stand and weigh another small test tube. Depending on what is being used, .61 g +.03
In stoichiometry and this lab, proportions or mass ratios are used to find the quantitative relationships between the reactants and products. Another topic that relate to this lab is the limiting reaction. Stoichiometry was used to find the limiting reaction of this reaction lab through proportions and conversions, which was lead (II) nitrate. Additionally, the excess reactant is another topic that relates to this lab. Stoichiometry was used to find the excess reactant which was potassium iodide. Another topic mentioned was the actual yield. The actual yield was used for lead (II) iodide. This data can be compared to the theoretical yield to find how well the experiment was performed. Additionally, the theoretical yield was used in this lab in order to find the percent yield. Another topic was the percent yield. The higher the percent yield, the better the experiment was performed. Another topic was double replacement. In the experiment the reactants are made of two elements that yields products which have been double replaced. In addition to the previous topics, uncertainty is another topic repeatedly used throughout the lab. The uncertainty is used during measurements to account for the room of error that was possibly made during the measurements. Molar mass was another topic that relates to the lab. In the proportions and conversions part of the lab, molar mass is used to correctly balance the
In the field of spectroscopy, absorbance is defined as the optical density (OD) of a substance as a logarithmic proportion of the luminescent radiation which contacts a material to the luminescent radiation which is transported through a substance (Zitzewitz 395). The λ maximum of a substance was empirically predicted by the Woodward – Fraser rules. These rules have the intention of forecasting the absorption spectrum of a material and its wavelength (Woodward 1123). Spectrophotometry is defined as the empirical and quantitative assessment of the reflection of luminescence conveyance of a substance in relation to the wavelength. Spectrophotometry normally incorporates the application of a spectrophotometer. This device assesses the robustness of the luminescence (Schwedt 16).
Part A- A vial was filled half way with a 0.2M ammonium nitrate solution, and clamped onto a ring stand. A small wad of cotton was packed tightly into the bottom of a medicine dropper. The dropper was filled two-thirds of the way with 0.1M copper (II) sulfate. The dropper was placed into the ammonium nitrate solution, and a bit more copper (II) sulfate solution was added. A piece of copper was added to the dropper. A half cell containing 0.1M Silver Nitrate and a wire of silver medal was prepare vial with the copper electrode. The voltmeter leads were attached to the copper and sliver electrodes so there as a positive reading. The initial Ecell was recorded along with the polarity. The half-cell reactions and the equation for the spontaneous cell reaction were written. Finally, the Nernst Equation was used to calculate the Eo for the cell.
tube. Add 6 mL of 0.1M HCl to the first test tube, then 0.1M KMnO4 and
Complexometric Titrations [homepage on the internet]. No date. [ cited 2014 Mar 20]. Available from: http://www.ciens.ucv.ve:8080/generador/sites/martinezma/archivos/EDTA.pdf
Thickett, Geoffrey. Chemistry 2: HSC course. N/A ed. Vol. 1. Milton: John Wiley & Sons Australia, 2006. 94-108. 1 vols. Print.
Gross, R., Abenojar, E. C., & Tan, J. A. (2010) Modern experiments in general chemistry II (3rd ed.). Ateneo de Manila University.
Plontke, R. (2003, March 13). Chemnitz UT. TU Chemnitz: - Technische Universität Chemnitz. Retrieved April 1, 2014, from http://www.tu-chemnitz.de/en/
...ceptor. So this means that the interaction between the Lewis acid metal center in Nickel II perchlorate, Ni(ClO4)2 and the Bronsted base ammonia, NH3, will create a complex. Complex in here means it is a molecular existence formed by two or more element entities (ionic or neutral), or the correlated chemical type. In simpler words, it means that it is a substance that is composed by two or more substances each that can be able to exist independently.