Simple Electrochemical Cells

1. Simple Electrochemical Cells The two demonstrations show simple electrochemical cell. An electrochemical cell consists of two different metals in electrolyte. The voltage depends on metals concentrations used. See Tables of Standard Reduction Potentials for quantitative guides. Please note the metals and the solutions used, and check the standard potential for the pairs of metals used in the demo. Draw diagrams of these cells. Represent these cells using cell conventions.

2. Electrolysis Electrolyses induce endothermic chemical reactions. Electric energy causes reverse of spontaneous reactions. Electrolysis of water, charging batteries, and electroplating utilize electrolysis. This demonstration shows the electroplating of chromium from a solution containing dichromate ions, Cr2O72–.

3. Metal Displacement Reactions These demonstrations show metal dissolving in solutions containing ions of metals that are less electrochemical reactive. The reactions demonstrated are: Zn (solid or metal) + Cu2+ (aq) = Zn2+ (aq) + Cu (solid or metal) Complete the following reactions. Which one will not no react? Fe (s) + Cu2+(aq) = Cu (s) + Ag+ (aq)= Pb (s) + Zn2+ (aq) = Zn (s) + Sn2+ (aq) =Ag (s) + Cu2+ (aq) = Please look up the standard voltages of these pairs on the Table of Standard Reduction Potentials.

4. Removing Tarnish on Silver What chemical principles are used to remove tarnish on silver? What are the metals in action, and what is the electrolyte? What chemical reactions take place? Apply these principles to other applications. Do you have any?

5. Reaction Rates and Equilibrium The major theme for Chem123 is chemical reaction rates and equilibrium. What factors affect the reaction rates? What factors affect the equilibrium? We have introduced methods to correlate quantities with these factors. The following segment shows qualitatively how these factor affects reaction rates and equilibrium. A Review