Activity 5-1 Reading Guide
Carefully read “Chem Talk”, Pages 356 through 358, in your textbooks.
Information:
Two quantities are used to describe a battery’s action, voltage and current. What do they describe?
Voltage: a measure of the difference in electrochemical potential between two electrodes.
Current: the rate of electron flow
What does the mnemonic “LEO says GER” mean? How is it used?
LEO: Lose Electrons Oxidation
GER: Gain Electrons Reduction
It is used to remember the two half-reactions of oxidation and reduction
Define: oxidation, reduction, anode, and cathode.
Oxidation: the process of a substance losing one or more electrons.
Reduction: the process of a substance gaining one or more electrons.
Anode: the negative battery electrode that removes electrons in an electrical circuit. In an
electrochemical cell oxidation takes place at the anode terminal.
Cathode: the positively charged electrode of an electrical device, such as a primary cell, that supplies
current.
Conceptualization:
How is energy stored in a battery?
One way to store it is in the form of chemical energy in a battery. When connected in a circuit, a battery
can produce electricity. If you look at a battery, it will have two ends & emdash; a positive terminal and
a negative terminal. If you connect the two terminals with wire, a circuit is formed. Electrons will flow
through the wire and a current of electricity is produced. Inside the battery, a reaction between the
chemicals takes place. But reaction takes place only if there is a flow of electrons.
Why is a battery called an electrochemical cell?
Electrochemical cells contain to half reactions that when in a closed circuit transfer electrons from the
losing electrons to the gaining electrons side.
In a battery, how do you tell which metal will be oxidized?
The metal that will be oxidized I your metal that will give up electrons and in an activity series the top
metals are your anodes and are the metals being oxidized
In a copper/zinc battery, the zinc gives up electrons, while in the aluminum/zinc battery, the zinc gains
electron. What does this tell you about the relative activity of the metals?
Some metals are special cases in which they don’t specifically give up or gain electrons but can do both.
Application:
Write a reaction showing a magnesium atom losing two electrons.
Mg(s) -> Mg {+2} + 2eWrite a reaction showing a lead (II) ion gaining two electrons.
2e- + Pb{-2} -> Pb(s)
Write a reaction showing the transfer of two electrons from a magnesium atom to a lead (II) ion.
Mg(s) -> Mg {+2} + 2e2e- + Pb{-2} -> Pb(s)
If you were to make an iron/nickel battery, which metal would be the cathode? How do you know?
The copper/zinc battery makes 1.1 V. What metals could replace the zinc to make a greater voltage?
Sketch a cadmium/lead battery. Describe what happens as the battery runs.