Transcript Simple Electrochemical Cells

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.
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–.
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.
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?
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