Electrochemisty

Question

9. Will Hg2+ ions react with water to produce Hg metal? Explain. Be careful, the overpotential

effect comes into play here!

Answer 1

I know when you dissolve a mercuric salt in water, that the mercuric ions do not react with the water to form metallic mercury. I'm talking about pure, distilled water; however, if the water is impure, and full of contaminants, you might see some reaction overnight. Fehling's solution, for example, will reduce Hg++ to Hg^o, which, under the right conditions, can cause the mercury metal to precipitate out as a silvery mirror on the walls of a test tube. When made with Ag+ insted of Hg++, and placed on a the cleaned surface of of flat glass, the reacting solutions deliver a beautiful, silver mirror. This makes a good demo.