Introduction: (Initial Observation)
Chemical energy stored in different substances can be converted to electrical energy. This ability is the work principle of most batteries (some known as dry cells).
Each battery has two poles usually made of two different metals. One pole is the positive pole and the other is the negative pole. Electrons can travel from negative pole to the positive pole via a conductor such as a wire.
Inside each battery there are chemicals that cause such chemical reactions. These chemicals in general are called electrolytes. A flow of electrons in a conductor is called electricity and if large enough, it can be used to make electro magnet, light up a light bulb or run an electric motor.
In this project you will make a salt water battery. In other words the electrolyte you use is saltwater. You will then perform a series of experiments to determine how does the amount of oxygen affect the life and the power of the battery.
Find out about batteries and how a chemical reaction can create electricity. Read books, magazines or ask professionals who might know in order to learn how different factors may affect the production of electricity using chemicals. Factors such as the type of electrodes and the type of chemicals may be studied.
Following are samples of information you may find:
What is a battery?
In electronics, a battery is a combination of two or more electrochemical cells which store chemical energy and make it available as electrical energy. Since its invention in 1800 by Alessandro Volta, the battery has become a common power source for many household and industrial applications, becoming a multibillion-dollar industry.
Why a saltwater battery?
We all know that the world is now facing an energy crisis and everyone is trying to do something about that. Now you can show everyone that electrical energy or electricity can be made from air and saltwater. After all, both the air and the saltwater are freely available everywhere. These are the two things that we have plenty of them.
This may seem impossible. I could not believe it myself the first time that I heard about it. It almost sounds like a magic trick. Finally, I decided to test it anyway.
I tried different concentrations of salt water, different temperatures, and different electrodes and had no success. It took me a few months thinking about it until I solved the problem in my mind and decided to repeat my tests again. This time everything worked fine and I was able to make enough electricity to light up a small light bulb.
The concept is easy. The same way that you burn wood and make heat energy, you should be able to burn metals and get electricity (or electrical energy). The difference is that you are not really burning any thing; instead, you are producing a condition for oxidization which by itself is the same as slow burning. So what you really do is oxidizing iron in saltwater using the oxygen from the air or any other source. (At least, that’s my theory at this time)
I don’t know if this method of producing electricity is economical and cost effective. What I know is that it is worth to try. If with one cup of salt water and some metals I was able to light up a small light bulb, maybe you can light up the entire building by a tank of salt water and a few hundred pounds of scrap metal.
No mater what is the results, I am proud that I can make an emergency battery for myself if I need it.
It took me a long time to make the first working battery using the salt water; however, you don’t have to waste that much time. I have combined the results of all my experiments and made a recipe for success. Just follow the instructions and you will get results in the first try.
Actually there are many different combinations of many different materials that can produce some electricity. Experimenting with saltwater and air is suggested for the younger students because these are relatively safer materials and are easier to obtain.
Where to buy the materials?
The main components of this project are available as a set in MiniScience.com online store and KidsLoveKits.com. This set will only include the essential components. You must have a plastic container, a wooden board, some iron and some hydrogen peroxide to complete your material.
This set includes 2 Magnesium electrodes, screws, light bulb, light base and insulated wire with alligator clips on both ends.
Where can I buy Magnesium electrode locally? Can I substitute the magnesium electrode with something else?
Technically you can use any other metal and you will still produce some electricity; however, that electricity will not be enough to light up a light bulb. Most students want to see the light and both students and teachers consider it as a proof of success. Magnesium metal and electrode are not available in general stores. You can only buy them online or from scientific suppliers. The magnesium electrodes MGFLAT and MGCOIL are successfully tested with this project.
What do you want to find out? Write a statement that describes what you want to do. Use your observations and questions to write the statement.
The first purpose of this project is to construct an Air/Saltwater battery and use it to successfully light up a light bulb.
The second purpose is to find out the answer to this question:
How does the salinity of saltwater affect the production of electricity in a saltwater battery?
When you think you know what variables may be involved, think about ways to change one at a time. If you change more than one at a time, you will not know what variable is causing your observation. Sometimes variables are linked and work together to cause something. At first, try to choose variables that you think act independently of each other.
Independent variable is the concentration of salt. Try 5%, 10%, 15% and 20% salt solutions.
Dependent variable is the output voltage in a closed circuit (when battery is connected to a light bulb).
Constants are the size, the specification and the design of the battery.
Control variable is the ambient temperature (room temperature). Record the room temperature to make sure there will be no big change in the room temperature in your different trials.
Based on your gathered information, make an educated guess about what types of things affect the system you are working with. Identifying variables is necessary before you can make a hypothesis.
This is a sample hypothesis:
I hypothesize that the concentration of saltwater has no effect on the production of electricity.
This is another sample hypothesis:
I hypothesize that the concentration of saltwater has a direct relation with the production of electricity. The more salt in water the more electricity will be produced.
Design an experiment to test each hypothesis. Make a step-by-step list of what you will do to answer each question. This list is called an experimental procedure. For an experiment to give answers you can trust, it must have a “control.” A control is an additional experimental trial or run. It is a separate experiment, done exactly like the others. The only difference is that no experimental variables are changed. A control is a neutral “reference point” for comparison that allows you to see what changing a variable does by comparing it to not changing anything. Dependable controls are sometimes very hard to develop. They can be the hardest part of a project. Without a control you cannot be sure that changing the variable causes your observations. A series of experiments that includes a control is called a “controlled experiment.”
Are you ready for this project: Before doing this project you must be familiar with simple electric circuits. In other words you must be able to light up a small light bulb by connecting it to a battery. This connection may be made by wires or by other conductive materials (such as a metal spoon or a safety pin.
You will start your experiment with clean salt water; however, the saltwater will become polluted during your experiment. Protect your hands and eyes from contact with polluted saltwater. The electrochemical reaction may release hydrogen and oxygen gases. Perform your experiments in a well ventilated place. Keep all materials and your experiment setup away from fire.
Experiment 1: Get a light
Introduction: The first and the most important step in this project is making an air/saltwater battery that really works and makes enough electricity to light up a light bulb. This by itself is a success and is enough for many students.
- Connect 2 magnesium coil electrodes to one alligator clip of a black connection wire.
- Connect some steel wool to one red alligator clip of a red connection wire.
- Connect the other end of the above wires to the contact screws of a lamp holder (as shown in the diagram). The alligator clips can hold the contact screws; however, you may also want to remove the alligator clip and directly connect the wire ends to the lam holder.
4. Screw the light bulb on the miniature base.
5.In a pitcher, prepare some strong, warm salt water. Add enough salt so at the end some salt will be left at the bottom of the pitcher.
6. Transfer the salt water from the pitcher to the experiment container. Make sure the depth of saltwater is about 4 to 5 inches.
7. Hold both electrodes and insert them into the saltwater in a way that they don’t touch each other.
8. At this time, if all the connections are secure and the electrodes are large enough, you should get a light.
9. Add one or two tablespoon hydrogen peroxide to the salt water. Does the amount of light increase?
10. If you did not get light, check your connections and your light bulb and then try again. If the light bulb is lit, then you have done good. Remove the electrodes and rinse them in clean water and save them for your future experiments or classroom demonstration.
How can I get more light?
- Make sure your electrodes are not touching each other.
- Make sure there is nothing blocking the space between the electrodes.
- Make sure that the alligator clips are not touching the salt water.
- Both electrodes must have the maximum possible contact surface with salt water.
How can I increase the contact surface of electrodes?
The test tube electrodes (magnesium electrodes in test tubes) are formed like a spring. This provides the largest possible surface contact. For Iron electrode you may use steel wool. Steel wool has a very large surface contact. A steel screen may work as well.
You may notice that you will get more light if you stir the solution or if you remove the iron electrode and insert it back again. Such actions provide oxygen to the surface of the iron.
Why do we add hydrogen peroxide?
The oxygen in the air may not be enough for your demonstration and you may get a dim light.
In this case you may add some oxygen (in the form of hydrogen peroxide) to the salt water. That should immediately increase the light.
A cup is relatively small. If you have access to a larger container, you will get a better result. In a larger container, it is easier to secure the electrodes in two opposite sides so they will not touch each other.
The electricity produced in this way may be used to light up a light bulb, an LED or run a low voltage electric motor.
Need an Experimental Project?
Students can perform many different experimental projects based on Air/ Saltwater Battery. Each of such experimental projects study the effect of one specific factor in the production of electricity. The purpose of all such studies is to obtain information needed to optimize the production of electricity in an Air/Saltwater battery. Any of the questions bellow may be used as a base or start point for a different experimental project.
- How does the salinity of saltwater affect the production of electricity?
- How does the amount of oxygen affect the production of electricity?
- How does the temperature of electrolyte affect the production of electricity?
- How does the pH of electrolyte affect the production of electricity?
- How does the type of salt affect the production of electricity? In addition to the table salt (Sodium Chloride) you may try Epsom salt (Magnesium Sulfate), Ammonium Nitrate, Potassium nitrate, copper sulfate or any other chemical salt.
Almost in all experimental projects you will need a voltmeter or a multimeter to measure the amount of electricity (Usually voltage) in an air/saltwater battery.
Multimeter or Voltmeter:
Any multimeter that can measure low range DC voltage may be used to measure the output voltage of your Air/Saltwater battery. Two common models are AMM360 and YG188.
Multimeter model YG188:
YG188 is an analog multimeter for general electrical use.
- 16 Position rotary function and range selector.
- Measures AC/DC Voltage, DC Current and resistance
- Integrated test leads.
- Includes rugged holster and full instructions.
Multimeter model AMM360:
AMM360 is a desktop analog multitester for measuring DC Volt, AC Volt, DC Current and Resistance. AMM360 can be used as a very sensitive galvanometer and can show as low as 0.01 DC voltage. AMM360 can also be used to test transistors and diodes.
Experiment 2: How does the salinity of saltware affect the production of electricity in an Air/Saltwater battery?
Introduction: Now that you have successfully made an Air/Saltwater battery you can test to see how does the concentration of salt affect the production of electricity. In this project you will need 5% saltwater, 10% saltwater, 15% saltwater and 20% saltwater.
- 5% saltwater may be made by mixing 50 grams of salt and 950 grams of water (950 ml of water is 950 grams). (You could also mix 1 ounce of salt with 19 ounces of water).
- 10% saltwater may be made by mixing 100 grams of salt and 900 grams of water (900 ml of water is 900 grams). (You could also mix 2 ounce of salt with 18 ounces of water).
- 15% saltwater may be made by mixing 150 grams of salt and 850 grams of water (850 ml of water is 850 grams). (You could also mix 3 ounce of salt with 17 ounces of water).
- 20% saltwater may be made by mixing 200 grams of salt and 800 grams of water (800 ml of water is 800 grams). (You could also mix 4 ounce of salt with 16 ounces of water).
- Prepare 5%, 10%, 15% and 20% saltwater solutions.
- Connect your light bulb to 2 magnesium electrodes from one side and some steel wool from the other side (as you did in steps 1 to 4 of the experiment 1).
- Connect the red probe of the multimeter to the red wire, where it is connected to the lamp holder.
- Connect the black probe of the multimeter to the black wire, where it is connected to the lamp holder.
- Set the multimeter to read DC voltage of up to 2.5 Volts.
- Get 4 identical cups or plastic containers. Fill each container with one of the saltwater solutions you have already prepared up to about 4 to 5 inches. Label them as 5%, 10%, 15% and 20% depending on the saltwater in each container.
- Insert the electrodes in the 5% saltwater. Make sure the electrodes are not touching each other. wait for 5 seconds and then read the voltage. Remove the electrodes. Hold them up for a few seconds so the excess saltwater on electrodes will drop.
- Insert the electrodes in the 10% saltwater. Make sure the electrodes are not touching each other. wait for 5 seconds and then read the voltage. Remove the electrodes. Hold them up for a few seconds so the excess saltwater on electrodes will drop.
- Insert the electrodes in the 15% saltwater. Make sure the electrodes are not touching each other. wait for 5 seconds and then read the voltage. Remove the electrodes. Hold them up for a few seconds so the excess saltwater on electrodes will drop.
- Insert the electrodes in the 20% saltwater. Make sure the electrodes are not touching each other. wait for 5 seconds and then read the voltage. Remove the electrodes. Hold them up for a few seconds so the excess saltwater on electrodes will drop.
- Repeat your measurements 2 more times starting from the 5% saltwater and ending by the 20% saltwater. Record your results in a table like this:
Make a graph
You can use a bar graph to visually present your results. Make a vertical bar for each of the salt concentrations you have used. Label the bars with the concentration of the saltwater they represent (5%, 10%, 15% and 20%). The height of each bar will be the average voltage you calculate for that concentration of saltwater. In a small graph you may use a 1″ bar to represent 1 volt, but in a large graph you may use a 10″ bar to represent one volt.
Materials and Equipment:
This is a list of materials you need for your experiment and you will most likely need to buy them.
- Miniature light bulb (low voltage, low current)
- Miniature base for light bulb
- Pair of insulated solid copper wire AWG=20
- Pair of alligator clips
- Magnesium Electrodes
- Iron Electrodes
- A cup of saltwater (not in the picture)
- Screws for the miniature base.
Additional materials and optional materials you need, but you may have them at home:
- A wooden board to mount the miniature base (light holder)
- Plastic container about 4″ x 4″ x 4″
- Hydrogen Peroxide
Results of Experiment (Observation):
Experiments are often done in series. A series of experiments can be done by changing one variable a different amount each time. A series of experiments is made up of separate experimental “runs.” During each run you make a measurement of how much the variable affected the system under study. For each run, a different amount of change in the variable is used. This produces a different amount of response in the system. You measure this response, or record data, in a table for this purpose. This is considered “raw data” since it has not been processed or interpreted yet. When raw data gets processed mathematically, for example, it becomes results.
Your completed data table including the averages you calculate will form your results.
For experiment number 2 you will repeat the test 3 times for each saltwater solution. You will need to calculate the average of your measurements for each salt solution. Write your calculations in this section of your project guide.
Summary of Results:
Summarize what happened. This can be in the form of a table of processed numerical data, or graphs. It could also be a written statement of what occurred during experiments.
It is from calculations using recorded data that tables and graphs are made. Studying tables and graphs, we can see trends that tell us how different variables cause our observations. Based on these trends, we can draw conclusions about the system under study. These conclusions help us confirm or deny our original hypothesis. Often, mathematical equations can be made from graphs. These equations allow us to predict how a change will affect the system without the need to do additional experiments. Advanced levels of experimental science rely heavily on graphical and mathematical analysis of data. At this level, science becomes even more interesting and powerful.
To summarize your results, make a new table that does not show the data, but it shows your final calculations:
Using the trends in your experimental data and your experimental observations, try to answer your original questions. Is your hypothesis correct? Now is the time to pull together what happened, and assess the experiments you did.
Related Questions & Answers:
What you have learned may allow you to answer other questions. Many questions are related. Several new questions may have occurred to you while doing experiments. You may now be able to understand or verify things that you discovered when gathering information for the project. Questions lead to more questions, which lead to additional hypothesis that need to be tested.
What is a good title for my project?
You can call it “Air battery”, “Salt water battery”, “electricity from air” or “electricity from the salt water”.
If you did not observe anything different than what happened with your control, the variable you changed may not affect the system you are investigating. If you did not observe a consistent, reproducible trend in your series of experimental runs there may be experimental errors affecting your results. The first thing to check is how you are making your measurements. Is the measurement method questionable or unreliable? Maybe you are reading a scale incorrectly, or maybe the measuring instrument is working erratically.
If you determine that experimental errors are influencing your results, carefully rethink the design of your experiments. Review each step of the procedure to find sources of potential errors. If possible, have a scientist review the procedure with you. Sometimes the designer of an experiment can miss the obvious.
List your References in this part of your report. Include books, websites and name individuals you interviewed.