Download LESSON 9 Electricity From Batteries

LESSON 9
Electricity From Batteries
Overview
In this lesson and the next, students will learn about the two basic ways
humans produce electricity: batteries and turbine generators. Students
will design, build and test their own batteries.
Student
Learning
Targets
• I can explain how batteries store potential energy in the form of
chemical energy.
• I can use an ammeter to measure the flow of electrical current.
• I can explain how an electrical current is produced from a battery and
draw you a diagram.
• I can explain how chemical energy is converted to electrical energy
(electricity) in a closed circuit.
NGSS
MS-ETS1-1.
Background
Define the criteria and constraints of a design problem with sufficient
precision to ensure a successful solution, taking into account relevant
scientific principles and potential impacts on people and the natural
environment that may limit possible solutions.
Most of our electricity is produced from batteries and turbine generators
at power plants. Photovoltaics is the exception, which we will discuss in a
lesson 13.
Batteries convert stored chemical energy into electrical energy through
an electro-chemical reaction. A battery has three parts: an anode with a
negative charge (-), a cathode with a positive charge (+), and the
electrolyte (see diagram on the next page). The anode and cathode are at
the opposite ends (called terminals) of the battery and are labeled with
the signs – (anode) or + (cathode). The cathode consists of an element or
a compound that easily loses electrons; and the anode consists of
element or compound that attracts electrons during the electro-chemical
reaction. The electrolyte consists of a liquid, paste or jell separating the
anode and cathode, but through which electrons easily travel. For
example, acid is used as the electrolyte in a car battery, and ammonia
chloride in an alkaline battery. Caution is needed when working with
batteries containing corrosive electrolytes. In our student battery we will
use harmless salt water as the electrolyte.
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When a complete circuit is made between the anode and cathode using a
wire, electrons flow from the cathode through the electrolyte to the
anode; and then to the wire and back to the cathode, producing
electricity. Current will continually flow through the circuit until the
battery is spent. In other words the chemical reaction inside the battery
stops because the anode material has been used up (see diagram).
Adapted from "How Do Batteries Work?" Welcome to QRG. Web. 03 Jan. 2012.
<http://www.qrg.northwestern.edu/projects/vss/docs/power/2-how-do-batterieswork.html>.
Typically, a type of load is available to connect the battery using wire. A
load can be anything from a light bulb, a motor, or an electronic device
such as a radio. Because the chemical reaction in a battery only takes
place when a wire is connected forming a complete circuit, a battery can
be left alone for years and still have enough power to be usable. A
battery’s capacity is the amount of electric charge it can store. The more
electrode material and electrolyte material, the greater the capacity of
the battery. Thus, a small battery with the same chemistry as a large
battery has less capacity.
Electronic devices typically need more than one battery to work. Several
batteries may be combined to create a higher voltage in an arrangement
called a series circuit. Multiple batteries may also be arranged in a
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Nagele, et al. 2016
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configuration called a parallel circuit, which increases current. For
example, if each battery produces 1.5 volts, then four batteries in parallel
will produce 1.5 volts, but with a current being four times that of a single
battery. Whereas in a series circuit arrangement, the four batteries would
produce 6 volts. For this reason a series battery circuit is used to operate
a single load that requires high voltage, whereas a parallel battery circuit
is used to operate multiple loads with the same voltage requirement that
a single battery can produce.
Electricity (electrons) flowing along the circuit is invisible. However, we
can see it working (such as lighting a bulb) and measure its flow with a
tool called a Volt-Ohm meter. The electrical source such as a battery,
gives electricity (electrons) a “push” through the circuit. This push, called
voltage, can be thought of as electrical pressure, similar to water
pressure in a hose. Electrical pressure is measured in volts; whereas, the
actual flow of electrical current is measured in amperes. Amperes,
commonly called “Amps” can be measured by an instrument called an
ammeter.
Vocabulary
anode, cathode, electrolyte, load, capacity, voltage, volts, Volt-Ohm
meter, amperes, amps
Resources
NDT Resource Center – a website with good graphics and explanation of
how electrical current is measured: http://www.ndted.org/EducationResources/HighSchool/Electricity/electricalcurrent.htm
Energy Story – website on energy with good information explaining
circuits, batteries, etc.:
http://www.energyquest.ca.gov/story/chapter04.html
How Stuff Works – an article that helps explain how electricity is
measured and the difference between amperes, volts, and watts:
http://science.howstuffworks.com/environmental/energy/question501.htm
Materials
For class
1 D cell battery
Overhead 1: Science Investigation Report
For each student team
Salt – enough for 1 Tablespoon per team
Copper & Zinc electrode sets
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250 ml beaker or jar
Milliamp meter
Set of alligator connecting cords (one black and one red)
Plastic spoon
150 ml distilled water for Trial 1
150 ml power drink with electrolytes for Trial 3
Overhead 1 or 1a: “Science Investigation Report: Making a
Homemade Battery”
For each student
Science notebook
Pencil
“Science Investigation Report: Making a Homemade Battery” handout
Preparation
Prepare materials for teams
Time
60 minutes
Procedure
1. Building A Battery Activity: Share with students that electricity can
be stored in and produced from batteries. “How many of you have
ever played with a battery operated toy or machine?”
2. “Today we are going to build a model of the inside of a battery so you
can see how they produce electricity. Open your science notebook
and at your table, list as many things as you can that use
stored/potential energy in the form of electricity to power. Let’s see
which table can list the most in two minutes. Go!” Share ideas.
3. Using the “How Do Batteries Work” illustration for reference from the
background information section or Overhead 2, draw the diagram of
a battery and label the parts the board. Explain to students that
batteries usually have two kinds of metal, one at each end, and a
chemical solution between them called an electrolyte. The electrolyte
solution produces chemical reactions with the metals when in a
closed circuit, freeing electrons from the atoms of the metals. Remind
students that electrons move from the cathode to the anode; specific
materials are selected by the battery manufacturer for the cathode
and anode because the (atoms in the) cathode material want to lose
electrons and the (atoms in the) anode material want to gain
electrons, allowing electrons to flow from the cathode to the anode,
creating electric current. Have students copy a simplified version of
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the illustration in their notebooks. Display for the students a D cell
battery and ask students to find the + and - ends/terminals.
4. Distribute the following materials to each team and ask them to use
the information they just learned about batteries to make a
homemade battery using the beaker at the casing for the battery
where the electrolyte is held. Have teams problem-solve how to make
their own battery. You might want to facilitate their thinking if
needed. Then have them connect the ammeter as the load to
complete the circuit (closed circuit).
Remind them that the battery won’t work until the circuit is closed
so electrons can follow a complete loop. Note: let students struggle
for a while as this helps them develop their problem solving and
critical thinking skills. For less advanced students you can show
them how to make a homemade battery as drawn below.
Materials: beaker, distilled water, two different metals, ammeter,
pair of alligator connecting wires.
"Make A Battery." ElectroWorks Teacher
Guide. Manassas: Need Project, 2009. 14.
Print.
5. Have students draw and label the parts of their battery in their
notebooks. Label: battery casing, anode, cathode, electrolyte, metal
wires, and load. Ask students to use arrows to show the pathway
electrons take through the circuit.
6. Distribute the handout “Science Investigation Report” (Overhead 1 or
1a for more advanced students) and facilitate completion by students
of the sections labeled “Materials” and “What Is Your Question?” as
you introduce the activity. In the trials provided, students will test
different electrolyte solutions to determine which produces the most
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electricity in their homemade battery. Thus, a question might be: of
three solutions (distilled water, salt water, and red Gatorade) which
will produce the most electricity in a battery? Students may generate
other satisfactory questions as well.
7. Lead a class discussion for possible hypothesis. Remind students the
principles of forming and writing a hypothesis. Also, remind them that
whether your hypothesis is proven correct or incorrect isn’t the
objective here, but rather understanding how to conduct a science
inquiry investigation to answer the question posed (or to engineer a
solution to a problem if using Handout 1a). All scientists form
incorrect hypotheses. What’s important is the new knowledge
learned and shared with the world from conducting science
experiments/investigations.
8. Instead of completing the “Data Collection” section of the Science
Investigation Report, Students will complete the “Making a
Homemade Battery” handout as their data collection.
9. Assign students to scientific teams of three or four students, and
distribute one copy of the “Making a Homemade Battery” handout to
each team. Instruct students that team members will take turns
completing each section of the handout “Making a Homemade
Battery.” Tell students to complete each trial using an ammeter to
measure the electricity produced from their battery using different
electrolyte solutions.
10. Tell students they can test if electricity is being produced with a tool
called an ammeter that measures the amount of electricity in
amperes, or amps for short. Demonstrate how to attach the meter
and how to read it. Attach alligator clips to the leads on the meter.
Attach the clip with the black label to a zinc electrode and the other
clip to a copper electrode. Observe the meter. Place the electrodes in a
beaker of water so they are NOT touching. Observe the meter to see if
there is a change. Note: the meters actually read milliamps, and will
read in the negative range if the alligator connecting wires are
connected to the wrong electrodes.
11. Team members will draw/design a diagram of the battery their team
will create as they do Trials 1, 2, and 3; each team member should
include input from all their team members. Tell them to keep in mind
all the parts of the battery you spoke of earlier. Distribute supplies to
each team.
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12. After the teams have completed Trials 1, 2, and 3 and carefully
drawn/designed their experiments on the handout “Making a
Homemade Battery,” team members will take turns writing answers
to questions 1, 2, and 3 on the handout, and draw conclusions
through analysis regarding their question and investigation.
13. When they have finished, ask them what kind/form of energy is
stored in the battery and is it potential or kinetic? How do they know?
Answer: potential because the energy in a battery is chemical. A
chemical reaction only takes place in a closed circuit, initiating the
electro-chemical reaction.
14. Have students recap how a battery produces electricity. When it isn’t
producing electricity, what is it doing? (storing potential energy)
Extension:
If time is available, have students practice their science inquiry skills
by posing a new question and designing an investigation to test their
hypothesis. Example: what will happen if we add another copper
electrode or another zinc electrode, or the same metal for both the
anode and cathode? Students can also experiment with other
available metals as anodes and cathodes.
Assessment
Score “Making a Homemade Battery” handouts designs or Science
Investigation report.
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RESOURCES
Video on dissection a battery
Watch the Upgrade team disassemble two types of batteries, revealing what's inside. This hack
could save you a few bucks if you're looking for good batteries to use in other projects.
http://www.youtube.com/watch?v=yUlg-cO9Q9A
metal cap (+)
carbon rod (positive electrode)
zinc case (negative electrode)
manganese (IV) oxide
moist paste of ammonium
chloride (electrolyte)
metal bottom (-)
You can find the above diagram and battery on a google search for images.
How do batteries work—homemade video that shows chemistry of batteries with diagrams and
candy…not bad
http://www.youtube.com/watch?v=CJK2kwF6Am4
EXTENSIONS (See handout “Extension for Lesson 1”)
Look inside a battery to see how it works. Select the battery voltage and little stick figures move
charges from one end of the battery to the other. A voltmeter tells you the resulting battery
voltage.
http://phet.colorado.edu/en/simulation/battery-voltage
worksheet to go along with this simulation was created by a HS teacher-check it out.
http://phet.colorado.edu/en/contributions/view/3258
How does a turbine work also has graphics on wind, solar, hydro and steam.
http://turbinegenerator.org/generator-works
Three ways to make a Homemade battery
http://www.wikihow.com/Make-a-Homemade-Battery
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