CHM120H5 Lecture Notes - Lecture 2: Spectrophotometry, Denticity, Coordination Complex
Document Summary
Chromium salts have many practical applications including tanning of leather, coating metals such as zinc with a protective oxide layer, and preservation of wood. A chromium salt can be prepared by the reaction of potassium dichromate with oxalic acid dihydrate as follows: K2cr2o7 + 7h2c2o4 2h2o 2k[cr(c2o4)2(h2o2)2]2h2o + 10co2 + 5 h2o (1) The k[cr(c2o4)2(h2o2)2]2h2o salt is a transition metal complex composed of octahedrally coordinated chromium (iii) in which the chromium is surrounded by two bidentate oxalate ligands and two monodentate water ligands. The purpose of this experiment is to synthesize the cis form of this chromium salt and analyze it for chromium content based on the characteristic blue-green colour of the cr3+ ion. The beer-lambert law states that concentration is a factor that affects absorbance. Using the measured absorbance of the synthesized chromium solution from the spectronic 200 spectrophotometer, the chromium content in the product will be determined using a calibration curve.
