EXPERIMENT 3 PREPARATION OF K3[AI(C2O4)3]3H2O Introduction The complex is obtained if aluminate is treated with oxalate 2Al+2OH+6H2O2[Al(OH)4]+3H2[Al(OH)4]+3H2C2O4[Al(C2O4)3]3+4H2O+2H+ Procedure Place 1g of aluminum shavings into a beaker, Cover with about 15cm3 of water and add slowly, a solution of potassium hydroxide (30cm3,20%). Vigorous effervescence occurs and additions must only be made When the initial reaction has ceased. After adding let the alkali boil to complete dissolution. Filter the solution and add portions of oxalic acid ( 14g in all) to the hot solution. Filter hot, cool and add ethanol (50cm 3). Further cooling and scratching the side of the beaker may be necessary to complete formation of the fine white needles. Wash crystals with ethanol and dry by suction on a Buchner. Dry and weigh the product. Calculate the percentage yield. Exercise You have synthesized the compound K3[Al(C2O4)3].3H2O 1. Identify the central metal ion, the ligand and the counterion 2. Classify the ligand (is it mono-, bi- or polydentate) 3. Identify the donor atom in the ligand. 4. Calculate the oxidation number of the central metal ion 5. Write down the formula of the complex ion; is it neutral, anionic, or cationic? 6. Give the IUPAC name of the compound. 7. Draw the structure of the compound 8. Would you expect the complex ion to have any isomers, if so what type of isomerism would it exhibit? Draw the structures of the isomers