Download ENERGY Fruit and Vegetable Clock Chemical Cell

ENERGY
Fruit and Vegetable Clock
Chemical Cell
Carlo Waldfried
Edited by Anne Starace
Abstract
Energy is an important concept in our everyday lives. This
module demonstrates chemical energy being transformed to
kinetic and thermal energy.
Keywords: energy, conservation of energy, electrolytes,
battery, electrode, chemical cell
Funded by the National Science Foundation and the University of Nebraska
Content Standards
K
1
2
3
4
5
6
7
8
4.2.1
8.2.1
4.3.3
8.3.3
History & Process Standards
K
1
2
3
4
5
6
7
8
4.6.2
4.7.2
Skills Used/Developed:
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Energy- chemical cell V 3.0 © University of Nebraska 2002
TABLE OF CONTENTS
I. OBJECTIVES...............................................................................................................................4
II. SAFTEY.....................................................................................................................................4
III. LEVEL, TIME REQUIRED AND NUMBER OF PARTICIPANTS.......................................4
IV. LIST OF MATERIALS............................................................................................................4
V. INTRODUCTION .....................................................................................................................5
VI. PROCEDURE...........................................................................................................................7
VII. FREQUENTLY ASKED QUESTIONS…………………………………………………...10
VIII. TROUBLE SHOOTING…………………………………………………………………..10
IX. HANDOUT MASTERS…………………………………………………………………….10
X. REFERENCES………………………………………………………………………………..10
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Energy- chemical cell V 3.0 © University of Nebraska 2002
I. OBJECTIVES
Students will:
-understand that food contains chemical energy.
-understand that chemical energy can be converted to other forms of energy.
-(older students) determine which materials work best in a chemical cell.
II. SAFTEY
Make sure that no one tries to drink the soda/juice out of the electrolyte cell!
Do not give away the fruits/vegetables used for the fruit and vegetable battery.
III. LEVEL, TIME REQUIRED AND NUMBER OF
PARTICIPANTS
LEVEL
This activity is appropriate for grades K-12.
TIME REQURED
Preparation involves buying fruit and fruit juice.
This activity takes from 15 - 30 minutes to complete.
NUMBER OF PARTICIPANTS
About 3 - 10 participants at a time
IV. LIST OF MATERIALS
fruit and potato clock
chemical cell ( plastic cup with different
strips of materials)
1.5 - 3 V DC motors
light bulb
fan (12 V DC, 60 mA)
buzzer (24 V DC)
patch cords (insulated wires)
to buy close to activity time:
fruits and/or vegetables (orange, lemon,
grapefruit, etc.)
can of coke, orange juice
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Energy- chemical cell V 3.0 © University of Nebraska 2002
V. INTRODUCTION
Our world is under constant change, which is possible because there is energy available
to be used in making the change. Without energy, the world would be completely static -- no
changes could occur. This module explains the different forms of energy and how they can be
used to make changes. The principle forms of energy can be categorized as:
kinetic energy
potential energy
chemical energy
heat (thermal) energy
Although you cannot create or destroy energy (we say that energy is ‘conserved’), energy can be
transformed from one type of energy into another type. One of the important characteristics of
energy is that it can be used to do work. Work is defined as force multiplied by distance. So
basically, moving things is doing work; you must apply a force to make them move a certain
distance. The harder you push and/or the farther you move something, the more work you are
doing. Often, you cannot actually see energy, but you can measure energy by its ability to do
work.
The different types of energy have different features and to understand changes between these
forms, we have to understand how each type of energy is different than the others.
Type of energy
kinetic energy
potential energy
heat or thermal energy
description
energy of motion
energy of position:
something that could
potentially be pulled by
gravity
energy due to temperature
chemical energy
energy stored in chemicals
solar energy
energy due to the sun
example
a moving car, a jogger
a piledriver, a bungee
jumper just before the
jump, a ball tossed in
the air
boiling water, a hot
piece of coal
a battery, gasoline,
food
solar cells
Energy is constantly being transformed from one form of energy to another. For example, the
human body uses food (which contains chemical energy) and converts it in our body into heat
(body temperature), kinetic energy (motion), or into a different type of chemical energy - fat.
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Energy- chemical cell V 3.0 © University of Nebraska 2002
The principle of conservation of energy is the most fundamental principle in the world.
Its applications and usages are so common to our everyday life, that often it is not perceived.
This module will help participants discover and explore various forms of energy and how they
interact.
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Energy- chemical cell V 3.0 © University of Nebraska 2002
VI. PROCEDURE
A.
1. Fruit and Vegetable Clock
2. Chemical Cell
Fruit and Vegetable clock:
Setup:
Place two fruit and/or vegetable items into the clock's trays. Insert two electrodes (black and
yellow) into each fruit and/or vegetable. Make sure that each energy source has a black ( zinc)
and yellow (copper) electrode for proper operation. Keep extra fruits and vegetables nearby as
needed.
Execution: The fruit and vegetable clock is in operation. To demonstrate that the clock is
powered by the fruits unplug one electrode to discontinue the electrical circuit and watch the
clock go blank.
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Energy- chemical cell V 3.0 © University of Nebraska 2002
Chemical Cell:
Chemical cell is just another name for a battery. The term “chemical cell” is more descriptive
than “battery” because it tells you it is using chemical energy.
Setup:
a) Mount two electrodes to the electrode holders of the plastic cup of the chemical cell and b)
connect the wires of the electrodes to a light bulb, the buzzer, or the fan. c) Keep a can of coke
and/or orange juice nearby.
Note that wire must touch the bulb at the side and bottom as shown in the picture above.
However, the bulbs in the kit may be placed in wire holders, which make sure the current gets to
the side and bottom of the bulb.
electrode
holder
plastic
cup
electrode
electrolyte
(coke/juice
etc.)
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Energy- chemical cell V 3.0 © University of Nebraska 2002
Execution:
Open the coke can or orange juice container and fill the plastic cup. This will power the buzzer.
(The light bulb requires more energy than the buzzer, so the bulb may not work for as many
combinations of electrodes and electrolytes as the buzzer. When trying new combinations, test
with the buzzer first.) The participants can also see that the coke/fruit juice etc. supplies enough
power to run the fan, small light bulbs, etc. For more advanced participants, a voltmeter and
ammeter can be connected to the electrodes of the chemical cell for accurate measurements.
Participants may try various combinations of electrodes to see which ones produce the brightest
light or highest voltage on a voltmeter. The participants will discover that if the same electrodes
are used on both ends, no voltage is produced. The following table lists some expected values for
various combinations of electrodes that are included in the chemical cell kit, i.e. carbon (C),
copper (Cu), lead (Pb), nickel (Ni), iron (Fe), zinc (Zn) and aluminum (Al).
∆V
C
Cu
0.35
Pb
0.8
0.45
Ni
0.95
0.6
0.1
Fe
1.15
0.8
0.3
0.2
Zn
1.45
1.1
0.6
0.5
0.3
Al
2.4
1.9
1.45
1.3
1.15
Cu
Pb
Ni
Fe
Zn
0.8
The actual measured voltages might differ from the values listed in the table, depending for
example, on the electrolyte solution (coke, orange juice, etc) used for the experiment.
This demonstrates that chemical energy (food) can be converted into kinetic energy (fan) and
heat energy (the light bulb will become warm). The human body similarly converts food energy
to supporting individual organ systems. These organ systems collectively maintain the human
body.
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Energy- chemical cell V 3.0 © University of Nebraska 2002
Cleanup: Throw away the fruits and vegetables. Empty the plastic cups and rinse. Rinse and
clean off the electrodes and return them to the box.
VII. Frequently Asked Questions
Why doesn’t it work to have two electrodes of the same element? Electrons must flow from
electrode to electrode to make a battery or cell. Some materials want to lose electrons and other
materials want to gain electrons. If two such materials are allowed to exchange electrons, they
will. This movement of electrons is what lights the light bulb. If the electrodes are made of the
same material, then they either both want more electrons, or they both want to lose electrons.
So, no exchange will be made.
VIII. Trouble Shooting
IX. Handout Masters
See page 10
X. References
For more information about chemical cells:
http://www.funsci.com/fun3_en/electro/electro.htm
For information about energy and work:
http://scienceworld.wolfram.com/physics/
(search for energy)
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Energy- chemical cell V 3.0 © University of Nebraska 2002
Record your
observations
about the
different
combinations in
the boxes.
carbon
copper
aluminum
lead
iron
zinc
nickel
carbon
copper
aluminum
lead
iron
zinc
nickel
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Energy- chemical cell V 3.0 © University of Nebraska 2002
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Energy- chemical cell V 3.0 © University of Nebraska 2002