Transcript Read page D-64 Activity 65 Title: Chemical Batteries Problem: What combination of metal makes the best battery to power a small motor? Hypothesis: If _____________,

Read page D-64
Activity 65
Title: Chemical Batteries
Problem: What combination of metal
makes the best battery to power a small
motor?
Hypothesis: If _____________, then
____________________________.
• What do a battery and a peanut have in
common when we consider them as a source
of energy?
• Does anyone know what goes on inside a
battery?
– Batteries are full of chemicals
– A battery is an energy transformer
– A chemical reaction releases electrical energy
– Batteries use two different materials, usually two
metals that serve as positive and negative
terminals
Electrolytes
• An electrolyte is a material capable of
conducting electricity that allows the current
to flow as it is released from the reaction.
• The electrolyte material in an alkaline battery,
for example, is potassium hydroxide or
manganese dioxide paste.
• The nature and the amount of materials inside
the battery determine how much potential
chemical energy is available.
Background Information: Batteries
• A battery is a device that transforms chemical
energy into electrical energy through a
chemical reaction.
• When a battery is put in a flashlight and the
light is turned on, a path for electron flow has
been connected.
• Different metals have different chemical
properties which makes some metals react
more readily because the electrons in the
more reactive metals are more loosely held
and are readily lost to other materials
Electrochemical Cell
Two different metals are placed
Electrons (current) flow from
in a salt
(the
themagnesium
more reactive
to the
In a solution
copper-and-magnesium
battery the
gives
up less
electrolyte)
andtoconnected
by a
Thiscopper
current
electrons
form positive
magnesium reactive
ions, andmetal.
positive
salt bridge
andthese
wire. electrons to form a coating
passes
a circuit.
If the
ions gain
of through
copper on
the
light bulb is in contact, and the
copper bar. The metals are called electrodes.
current is sufficiently strong, the
bulb will glow
Reactivity of Metals
Hint: Free electrons are produced during the
reaction in a battery, electricity is the flow of
electrons.
Reactivity of Metals
Metal
With Copper Chloride
Magnesium
Reacts rapidly
Aluminum
Reacts rapidly
Zinc
Reacts Slowly
Iron
Reacts Slowly
Copper
No reaction
Materials
Each Bin Should Have
• 1 30-mL dropper bottle of 3%
hydrogen peroxide solution
• 1 small piece of sandpaper
• Roll of Masking Tape
And should have 2 sets of
• 1 SEPUP wet cell chamber
• 1 1.25 cm x 37.5 cmx32.5 mm strip
of each of the following metals:
–
–
–
–
•
•
•
•
•
•
copper
iron
magnesium
zinc
5 packages of table salt
1 plastic spoon
1 50-mL graduated cylinder
2 wire leads-one red and one black
1 27O-mL (9-oz.) plastic cup
1 electric motor
Procedure Part A
• Make a flag with the masking tape
• You will use the motor to measure how much
energy your battery produces by observing
how quickly the shaft turns.
• Connect one end of the red jumper cable to
the pin on the motor marked with a red dot.
• Connect the black cable to the other pin.
– One person should hold the motor during each
battery test and count how many times the shaft
turns in 10 seconds.
– All group members must make observations
Important Hints
1. One person is to hold the motor.
2. The masking tape “flag” should be small and not
touch the motor. After the connections are made,
you may gently push the flag to help the motor
begin turning.
3. Before lowering the metal strips into the wet cell
solutions, attach each lead to the motor and to one
end of a metal strip. Some of the reactions last only
a few seconds, so don’t lower the metal strips into
the solutions until you are prepared to make your
observations.
4. At the beginning of each test, use a piece of
sandpaper to clean the surface of the metals.
Procedure Part B
• Stop after part A
• Write Activity 65 Preliminary Questions
• With your group, design an investigation to
test the other combination of metals.
1. What is the purpose of your investigation?
2. What will you observe or test?
3. What materials will you need to conduct your
investigation.
4. How will you record your observations?
5. How will you use the results to make a
conclusion?
Procedure Part B:
1. Pour the electrolyte into the SEPUP wet cell
2. Connect the wire leads to the motor and the metal strip
combinations as described in table 1.
3. Lower two strips of different metals into the outside slots
of the SEPUP wet cell. There should be a small amount of
metal sticking out of the cells.
4. Give the flag a push if necessary and observe the motor
spinning for 10 seconds.
5. Record observations in a data table.
6. Disconnect the wire leads. Remove the two metal pieces.
Dry them, and then clean both sides with a piece of
sandpaper.
7. Repeat Steps 2-6 for all the metal combinations listed on
table 1.
Follow-up
• Fill in the information for table 2
• What do you conclude from your data?
• Do you have any ideas why some
combinations worked better than others in
providing energy for the motor?
Part C:
By analyzing the results of many
experiment involving metals
reacting with each other, scientists
have produce a table of metal
activities that help us predict what
will happen in any pairing of two
metals.
Major Concepts:
• A battery transforms potential
chemical energy into electrical
energy.
• When the circuit is completed,
electrical current is allowed to flow
from the negative pole of a battery
to the positive pole.