Experiment 1 – Preparation and Analysis of an Oxalatoaluminate Complex.
Appearance of oxalatoaluminate complex: A fine white powder
Yield and of the oxalatoaluminate complex
Weight of bottle = 19.15g Weight of final product + bottle = 27.88g
Yield of the final product = Weight of final product = (19.15-27.88) = 8.73g
Molecular mass of Aluminium = 26.9815g mol-1
Mass of aluminium used = 1g
Moles =
RMM of oxalatoaluminate complex = 408.2644g mol-1
Mass of product = 8.73g
Moles = Percentage Yield = =
Qualitative analysis of the complex and balanced equations:
Reaction with KMnO4:
Upon adding KMnO4 to the oxalatoaluminate complex and heating this mixture there was a notable colour change from the characteristic purple colour of the KMnO4 to a brown coloured solution. This may be due to Mn ions being reduced to another oxidation state leading to a colour change. A possible reaction from this could be:
2MnO4+(aq) + 16H+(aq) + 5C2O42-(aq) ----10e----> 2Mn2+(aq) + 8H2O(l) + 10CO2 (aq)
Reaction with AgNO3:
A cloudy white precipitate was formed when AgNO3 was added to the oxalatoaluminate complex which was likely due to the silver ions in solution reacting with the oxalate ligands bonded to the Aluminium ion central to the bidentate ligands.
Reaction with NH3:
Again, a white precipitate was formed when NH3 was added to the oxalatoaluminate complex. This is due to the dissociation of NH3 and water behaving amphoterically (in this case as an acid) to donate a proton to form NH4+ and OH- respectively. The central aluminium ions formed coordinate bonds with the ammonium ions to form a complex of [Al(OH)6]. This formed a white precipitate because it was insoluble in the
