23.1. Electrochemical Cells http://www.ck12.org
Lesson Summary
- Electrochemistry is the interconversion of chemical energy and electrical energy. Electrochemical reactions
are redox reactions. - The elements at the top of an activity series are the most easily oxidized, while the lowest elements are the
most difficult to oxidize. - A direct redox reaction cannot be used to generate an electric current. The oxidation and reduction half-
reactions must be separated, as in a voltaic cell. Voltaic cells use spontaneous redox reactions to generate a
current. - Dry cells, lead storage batteries, and fuel cells are three modern devices that take advantage of electrochemical
reactions to produce energy.
Lesson Review Questions
Reviewing Concepts
- What type of reaction drives any electrochemical process?
- Manganese metal is more active than cadmium. Which element is more easily oxidized?
- What half-reaction occurs at the cathode of a voltaic cell? At the anode?
- What substance is oxidized in a typical dry cell? What substance is reduced?
- What is the function of the salt bridge of an electrochemical cell? Why should an inert electrolyte be used in
the salt bridge?
Problems
- Predict whether a reaction will occur when the metals listed below are immersed into the given solutions.
Explain.
a. tin into nickel(II) nitrate
b. magnesium into lead(II) nitrate
c. lead into silver nitrate
d. silver into copper(II) chloride - For those experiments in question 6 in which a reaction occurs, write the following.
a. the balanced molecular equation
b. the balanced net ionic equation
c. the oxidation and reduction half-reactions - A voltaic cell is constructed with a strip of aluminum metal immersed in a 1 M solution of aluminum nitrate
as one half-cell and a strip of tin metal immersed in a 1 M solution of tin(II) nitrate as the other half-cell. The
half-cells are connected by a conducting wire and a salt bridge.
a. Write the oxidation half-reaction that will occur when the cell is operating.
b. Write the reduction half-reaction that will occur when the cell is operating.
c. Write the balanced overall redox reaction. - Depict the voltaic cell from question 8 in shorthand cell notation.
- What are the primary advantages and disadvantages of fuel cells compared to conventional power plants?