[aberneth]

I came upon an anomaly a few days ago. Nobody in my school's science department can explain it. We were doing an activity series/stoichiometry lab in my general chem class. We put zinc stripped nails into 1 molar Copper Chloride solution- that is, most of the class. The teacher didn't prepare enough, so I substituded for 1 molar copper nitrate. In the copper chloride vessels, a fine powdery crystaline structure evolved on the surface of the nail, whereas the copper nitrate vessels plated out into a solid coating. I am very interested to find out why the copper nitrate acted differently than the copper chloride.

[Borek]

Copper in the CuCl₂ is mostly in form of copper chloride complexes, thus it may behave differently. Check what will happen after using copper nitrate solution with NaCl added.

[aberneth]

thank you, that worked. My teacher and I are planning to explore this further using different sodium compounds. Our hypothesis is that the larger anions have stronger solvent shells, which act as a dampener, reducing the kinetic energy of the copper ions that collide with them. We are setting up an array of 200 test tubes, testing with 10 salts on 5 concentrations, on 4 levels of heat.

[Borek]

IMHO it'll be enough to start with several concentrations of NaCl - that'll show if the general idea of chlorides complexation is OK. Don't go for many anions, but rather for - say - three that are known to create copper complexes. You may try ammonia as well. Then learn how to calculate concentration of free copper ions (Cu²⁺) in these solutions (I can help you here) and see if there is a dependency between theri concentration and final effect.