we are redoing our first year laboratory, and want to fix a broken experiment, and add a new one.
1) Vanadium. We have the students make a variety of vanadium compounds and watch the color changes during a variety of redox reactions. I haven't taught this in a while, but I know there is a chemical reduction, bubbling air through it for an oxidation, and then finally reduction with zinc amalgam. We'd like to remove the Zn and Hg from the lab if possible. Does this lab sound familiar to anyone? And do other reducing agents work?
2) Werner compounds. We'd like to "adapt and implement" a Werner complex lab. Have the students make, say, cis and trans Co(en)2Cl2 or Co(NH3)4Cl2. Ideally, the two complexes would have dramatically different colors and properties. I suppose we could even have them make [Co(NH3)6]Cl3; [Co(NH3)5Cl]Cl2, [Co(NH3)4(Cl)2]Cl and [Co(NH3)3Cl3], or have groups make each one and compare as a class. Any ideas?