Experiment on: Chromium (III) Complexes Objectives The experiment was carried out in order to synthesize cis-disaquabis(oxalato) chromate (III) dihydrate, a substituted complex and potassium tris(oxalato)chromate (III) trihydrate, investigate their properties as coordination complexes and to observe their reactions in aqueous acid, base and salt. Introduction Coordination compounds such as those synthesised in the experiments carried out are composed on ligands and metal centres. The metal centre Chromium (Cr) is common to both products. Chromium is a group 6 d-block metal element which exhibits varied oxidation states, +6(CrO2F2), +3 (CrCl3). +2 (CrBr2) and the less abundant +5 and +4. The most common of which is Cr+3 (Housecroft & Sharpe, …show more content…
Ligands also exhibit various denticity, which dictates the number of atoms they donate to the central atom. C2O4, (oxalate) the ligand used in both experiments is a bidendate, chelating ligand. This ligand is represented as [ox]2- and donates two electrons and hence forms chelate rings. Water acts as a ligand in cis-K[Cr(C2O4)2(H2O)2]•2H2O, therefore, four electrons are donated in total from oxalate and two from water ligands. However, in K3[Cr(C2O4)3]•3H2O, the water occupies …outer coordination sphere. This is also a more stable complex as three bidendate ligands are bound compared to two monodendate and one bidendate in the former product (Housecroft & Constable, …show more content…
The solid was then left to dry in air and weighed. Preparation of potassium tris(xalato)chromate (III)trihydrate 20cm3 of distilled water was put into a beaker which was placed on a hot plate. 9.02g of oxalic acid was added in the beaker and stirred. The temperature was monitored with a thermometer till it reached about 50°C and all the solid was dissolved. Small aliquots of 3g potassium dichromate were then added. Heating was resumed and when there was no more visible reaction, 3.5g of potassium oxalate was added. The beaker was then cooled in ice for about 8 minutes. 4cm3 of ethanol was added and the beaker was swirled. Vacuum filtration was carried out and the solid product was washed in an 8cm3 solution of 50:50 ethanol and water. About 4cm3 of ethanol was thereafter used to wash the product. This weight of this product after drying was then recorded. Recrystallization was undergone from a mixture of ethanol and water and the product obtained filtered. Dichroism test A small amount of the product from both reactions was dissolved in about 4mL of water in a test tube. The test tube was the observed in light, to check for occurrence of two
This paper describes the methods used in the identification, investigation of properties, and synthesis of an unknown compound. The compound was identified as calcium nitrate by a variety of tests. When the compound was received, it was already known to be one of twelve possible ionic compounds. The flame test identified the presence of the calcium anion in the compound. The compound tested positive for the nitrate cation using the iron sulfate test. At this point it was hypothesized that the compound was calcium nitrate. Reactivity tests and quantitative analysis comparing the unknown compound with calcium nitrate supported this hypothesis. Synthesis reactions were then carried out and analyzed.
We thank the University of Oklahoma and the chemistry faculty for providing the space, instructions, and equipment for the development of this report and experiment.
and brought to a boiling temperature then filtered out the final product is converted to
The goal of this experiment is to determine which products are formed from elimination reactions that occur in the dehydration of an alcohol under acidic and basic conditions. The process utilized is the acid-catalyzed dehydration of a secondary and primary alcohol, 1-butanol and 2-butanol, and the base-induced dehydrobromination of a secondary and primary bromide, 1-bromobutane and 2-bromobutane. The different products formed form each of these reactions will be analyzed using gas chromatography, which helps understand stereochemistry and regioselectivity of each product formed.
The given lab experiment had two parts within it.. The purpose of this assignment was to help student make better prediction, to observed chemical reactions, to designing the experiment, and to make a claim from the results of the experiment. The two activities that will be completed are Activity A: Sink or Swim , and Activity B: Dissolving Chemicals in Water.
Then the reaction tube was capped but not tightly. The tube then was placed in a sand bath reflux to heat it until a brown color was formed. Then the tube was taken out of the sand bath and allowed to cool to room temperature. Then the tube was shaken until a formation of a white solid at the bottom of the tube. After formation of the white solid, diphenyl ether (2 mL) was added to the solution and heated until the white solid was completely dissolved in the solution. After heating, the tube was cooled to room temperature. Then toluene (2 mL) was added to the solution. The tube was then placed in an ice bath. Then the solution was filtered via vacuum filtration, and there was a formation of a white solid. Then the product was dried and weighed. The Final product was hexaphenylbenzene (0.094 g, 0.176 mmol,
The mixture was poured through a weight filter paper and Sucrose washed with a 5ml of dichloromethane. The resulting solid was left in a breaker to dry for one week, to be measured. Left it in the drawer to dry out for a week and weighted it to find the sucrose amount recovered amount.
see how this affects rate of reaction; in what way and if there is a
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.
In our experiment we utilized the hydrate cobaltous chloride. Hydrates are crystalline compounds in which one or more molecules of water are combined with each unit of a salt. Cobalt (II) chloride hexahydrate is an inorganic compound which is a deep rose color in its hydrated form. As an inducer of
This textbook introduces students to key concepts and processes related to organic and inorganic chemistry, analyzing compounds and using standard laboratory equipment. If the goal is to become a practicing chemist students will a bachelor's degree and some positions required advanced
The solvent should be easily removed from the purified product, not react with the target substances, and should only dissolve the target substance near it’s boiling point, but none at freezing. A successful recrystallization uses minimum amount of solvent, and cools the solution slowly, if done to fast, many impurities will be left in the crystals. Using the correct solvent, in this case ice water and ethyl acetate, the impurities in the compound can be dissolved to obtain just the pure compound. A mixed solvent was used to control the solubility of the product. The product is soluble in ethanol an insoluble in water. Adding water reduced solubility and saturates the solution and then the crystals
Thickett, Geoffrey. Chemistry 2: HSC course. N/A ed. Vol. 1. Milton: John Wiley & Sons Australia, 2006. 94-108. 1 vols. Print.
(Khan): further states, here L are the Ligand and which is formed via the complete replacement of water molecules by other ligands can occur till the formation of the MLn complex. “n” is the coordination number of the metal ion and represents the maximum number of monodentate ligands which can be bound to it [8]
This is because the physical properties and relative stabilities of metal compounds relate to the nature and disposition of ligands in the metal coordination spheres. Coordination chemistry refers to the chemistry of compounds formed by metals (Lewis acids) bonded to inorganic ions or molecules, or organic molecules, or their ions (Lewis bases) through donations of lone pairs of electrons.4 These coordination compounds can be ionic or neutral in nature and contains the metal ions/atoms closely surrounded by electron donor groups called ligands. This applies both to pyrometallurgy and