Determination of the Composition of Cobalt Oxalate Hydrate
Partner: Debnil Chowdhury
TA’s: Russell Dondero & Sylvester Mosley
February 9, 2000
The purpose of this lab was to determine the percent cobalt and oxalate by mass, and with that information, the empirical formula for cobalt oxalate hydrate, using the general formula Coa(C2O4)b.cH2O.
The powdered cobalt oxalate hydrate was weighed to about 0.3 g and placed in a pre-weighed crucible. The crucible and the cobalt oxalate were then heated until the cobalt oxalate decomposed into a stable, black solid, or Co3O4. Once the crucible was sufficiently
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First the moles of the Co3O4 were calculated, then the moles of Co, and finally the weight of the Co was found by dividing the moles by the molecular weight. For example: (0.1777g Co3O4)*moles/(241g) = 7.37x10-4 moles Co3O4; three Co per molecule means 0.00221moles Co; and the weight of Co is (0.0022 moles Co)*(59g/mole) = 0.13051gCo. The percent mass of parts of the cobalt oxalate hydrate were determined by using the equation (mass of part)/(mass of whole), where the part can be and ion or group of atoms and the whole is the entire molecule. For example, mass of the cobalt = .13051g and the mass of the molecule is 0.3012g, (0.13051g)/(0.3012g) = .4333 = 43.33%. The average percent of Co in Cobalt Oxalate Hydrate was then found by averaging the two