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EXPERIMENT 4PREPARATION OF POTASSIUM TRIS (OXALATO)-ALUMINATE (III) TRIHYDRATEOBJECTIVE:Upon completion of this experiment, students should be able to synthesis potassium tris(oxalate)-aluminate(III) trihydrate.INTRODUCTION:Aluminium (Al) is located in p-block with principal oxidation state of 3+. The Al surface isprotected from being oxidized by a layer called aluminium oxide (Al2O3). When Al2O3dissolvesin excess hydroxide, the aluminium hydroxide, [Al(OH)4]-ion is formed (eq 1). The addition ofoxalic acid, (H2C2O4) will produce the dioxalatoaluminate ion, [Al(C2O4)]3-and subsequentlyneutralize the excess hydroxide ion, OH-. The [Al(C2O4)]3-will be precipitated as potassium saltby addition of ethanol. Al2O3+ 2OH-+ 3H2O 2[Al(OH)4]-Al + 3KOH + 3H2C2O4.2H2O K3[Al(C2O4)3].3H2O + 6H2O + 3/2H2
MATERIALS:Potassium hydroxide, KOHOxalic acid dehydrate, H2C2O4.2H2OEthanolAcetoneDistilled waterIceAluminium foilBeaker 250mLGraduated cylinderFilter paperWatch glassHot plateGlass rodBuchner funnelMETHODOLOGY:1.0.50g aluminium foil that been cut to 1cm