The Composition Of Complex Ions In Solutions

The Composition Of Complex Ions In SolutionsIn this experiment, we are necessary to determine the composition of complex ion by continuous variation method. Complex ions refer to a metal cation bonded to either peerless or more than one molecules. It is a stepwise process to produce the complex ion because every process has its own equilibrium constant (Gretchen E. Potts,2001). However, continuous variation method involves the continue changing of the different concentration of the solution.Besides that, spectrophotometric method brush aside be use to quantitatively identify the unknown composition or concentration of a experiment solution with compare to a sample with known concentration. Then, spectrophotometer refers to an instrument which we can use it to measure the luminousness intensity. As we know, most of the UV-Vis spectrophotometers have a hunt down of the wavelength between 190nm-1100nm. This range lies between UV and Visible light region. (Frans F,2004)In this ins trument, it has 2 light sources. D2 and W lamp are used for UV and Visible light respectively. It will ensure that only monochromatic light will flow through the slit. Reference cuvette is used as a blank. At the end we can get the reading from the detector.Furthermore, Beer Lambert law states that when a monochromatic radiation highwayes through a transparent solution, the intensity of the absorbed radiation is directly proportionate to the concentration (c) and the optical pathlength, (l) of the solution. So, Absorbance, A = x l x c , where is the molar absorptivity.The materials we used during the experiment are Ammonium press out (III) sulphate and Salicylic acrid. Therefore, we used the following method to determine the concentration of the iron (III) salicylic acid complexes.Materials and Methods 500 cm3 of Ammonium iron 500 cm3 of salicylic acid solution(III) sulphate solution was prepared. was prepared. optic density of the other samples were determined using the sam e instrument and wavelength.The most suitable wavelength for measuring was determined.These mixture was then measured using spectrometer everywhere the range of 350-700nm.cuvetteResults From the spectrum, the level best peak has a wavelength of 531.5 nm.With the same wavelength, we obtained the following Absorbance for different samples and the data was recorded in the following table.Discussion From the results above, the molecular ratio of the Fe3+- salicylic acid complex by using Jobs method was 11. The complex is formed by which the salicylic acid donated its lone pair electrons from hydroxyl oxygen atom to iron metal. This is because, salicylic acid is a bidentate to the metal ion. Therefore, it needed three salicylic acid to donate its lone pair electrons to the iron(III) ion. So, the complex formed is trisalicylateferrate(III). The structure will be drawn as follow In this experiment, we measured the absorbance of our samples from UV-Vis spectrometer. The sample was poured into a cuvette. The sample was not destroy which means that with the using of this spectrometer, the sample was non- destructive. The UV- Vis light pass through the cuvette and the light was absorbed by the sample. Therefore, the sample must be in liquid form.Besides that, before salmagundi of Fe3+ and salicylic acid, the two solutions were glossaryless. However, after mixing the two solutions, the sample had a violet in colour. So, they can absorb visible light and because of the electrons from d orbital was excited from one to another electronic state. The complex gave violet in colour is because it absorbed green light and let the other light passed through. Green light is a complementary colour to the violet light, so the complex gives the maximum absorbance at wavelength 531.5 nm.In addition, we normally will select the maximum absorbance is because its sensitivity to the concentration of the solution is the greatest at the maximum wavelength. If the max is not the analytical wavelength, strong radiation may be strongly absorbed and caused deviation from the Beer Lambert Law. However, in this experiment, if let claim we did not use themax, the result we obtained from graph will not be affected much. We will also need to round off it to integer so that we can get the ratio.Furthermore, stoichiometry formula of a complex ion can be obtained through continuous variation method. Besides that, this method is actually help in the maintaining the number of moles of the sample throughout a series of different mixture in the sample. However, only different is the mole fraction of the different samples.Conclusion The maximum peak for iron(III)-salicylic acid complex was 531.5 nm.The molecular ratio of the Fe3+- salicylic acid complex is 1 1