The main goal of this project was to convert chemical energy to another form of useful energy. My group wanted to do a modified version of a lemon battery. On the Marin County 4-H All Star we found a project where they used play dough made out of lemon juice to carry an electric current from a battery to a LED (the button down below links to the page). We thought if we exchanged all the water for more lemon juice that we could create a battery out of it. We also made a Gatorade battery because we wanted to see how the two batteries compared to each other. The end goal of my group's project was to light an LED the most efficiently with one of the two batteries.
Content
Chemical Energy:
energy stored in the bonds of chemical compounds, this energy may be released during a chemical reaction, often in the form of heat
Anode:
the positively charged electrode by which the electrons leave a device
Cathode:
the negatively charged electrode by which electrons enter an electrical device
Reactive Series:
the most reactive element is placed at the top and the least reactive element at the bottom. More reactive metals have a greater tendency to lose electrons and form positive ions
energy stored in the bonds of chemical compounds, this energy may be released during a chemical reaction, often in the form of heat
Anode:
the positively charged electrode by which the electrons leave a device
Cathode:
the negatively charged electrode by which electrons enter an electrical device
Reactive Series:
the most reactive element is placed at the top and the least reactive element at the bottom. More reactive metals have a greater tendency to lose electrons and form positive ions
Presentation
Proof of Efficacy
In this project as a group we wanted to create and test two batteries to observe the similarities and differences between the two. The first battery we made was “Electric Playdough”, we made regular playdough, but substituted water for lemon juice. We thought the lemon juice in the dough would have a similar amount of energy as a lemon battery to light an LED. In the end, the dough was not able to light the light, but there were some energy transfers because we were able to record the difference volts from the dough. In this battery, a reaction must take place to have an electrical current, the electrons inside the metals want to move from a higher reactive metal to a lower one. The anode strip has as a lower reactivity so the oxidation reaction occurs here and the cathode strip has a higher reactivity so the reduction reaction occurs here. This allowed for the electrons to move, but the reactions required when there was acid, salt, or electrolytes between the anode and cathode strip. The second battery we made was a gatorade battery. In this battery, we wanted to test if the electrolytes inside of gatorade was strong enough to light a LED. We were not able to light an LED with this battery because the current was not strong enough in the battery to power a LED. The electrochemistry behind this battery is the same as the play dough. The electrons in the metals react with the electrolytes in the gatorade so the electrons move in a circuit from the anode to the cathode.
We changed many parts of our batteries during this project to see if we could get a LED to light up. In our playdough, we first tried adding more cells because it does not matter how large each cell is, it will still have the same amount of potential energy. We did this to see if we could get a higher voltage out of the dough which we were able to accomplish. The second thing we tested with the playdough was the materials used for the chemical reaction with the metals. We broke the dough into four pieces; the control, the one with more lemon juice, the one with more salt, the one with equal parts of lemon juice and salt. We thought if we added more lemon juice it would decrease the resistance the dough had on the current because the dough was more of a slime than it was a moldable dough. When we added more citric acid (C6H8O7), there was more citric acid to dissolve in water and this allowed for more hydrogen dissociates from the rest of the acid to form the ions H+ and C6H7O7-. These ions allowed more current to be able to run through the dough making it a more efficient battery. We were able to to increase the voltage of the battery from 0.64v to 0.8v. This still was not enough to power a LED, but we were closer to a working battery. We thought if we added more salt (NaCl) to our dough we could increase the amount ions in the dough because this would allow it to conduct a higher voltage and current. We were able to produce a higher voltage (0.64v to 0.8v) because we added more salt than there was lemon juice already inside the dough. Since we got positive results from both of our tests we thought by adding equal parts of lemon juice and salt to the third test ball would increase the voltage and current enough to light a LED. This made our playdough less efficient than before because the salt ions were reacting with citric acid ions to cause a double displacement reaction, which directly decreased the amount of ions in our solution, which which led to a decreased efficiency of the dough. The ions in the salt Na+ and Cl- where combining with to ions in the citric acid H+ and C6H7O7- to form HCL and NaC6H7O7, this means that very a little electric current was being produced by the reaction on the anode and cathode. We also thought that adding both lemon juice and salt to the gatorade battery would make it more efficient. Like the electric playdough, when we added the salt and lemon juice it made the battery less efficient for the same reasons that it made the electric play dough less efficient. We also thought that switching zinc out with magnesium would cause the battery to be more efficient because magnesium is farther away from copper on the reactivity series than zinc. This allows for a larger reduction reaction and a faster current which we thought could help us power our LED. When we did this it caused tremendous improvement in both of our batteries.
Our energy was moved from the electrons in the magnesium wanting to move to another metal that was lower on the reactivity series. This meant that the magnesium the first reacted with the citric acid (playdough) or electrolytes (gatorade). The oxidation reaction allowed for the energy to flow to where the reduction reaction took place (copper strip), after the reduction reaction the energy is able to flow through wires to the LED. Theoretically our first battery, lemon juice playdough with copper and zinc, should have worked because the copper have a half reaction of 0.337v and zinc has a half reaction of -0.763v. When one subtracts the anode from the cathode, you should get I.337-(-.763)I= 1.1v. In reality, we got 0.64v, which means we lost 0.46v, the energy could have been lost due to electrical resistance in the playdough. When we tested the battery that used magnesium and copper, we had lost a large portion of the potential energy. Copper has a half reaction of .337v and magnesium has a half reaction of -2.37v which means that when one subtracts the anode from the cathode you should get I.337-(-2.37)I=2.707v. We should have had enough energy to power a LED, but the battery was not able to power a LED, this again can be due to the resistance the dough had on the electrical current.
In the end, we were never able to get either battery to work, but we were able to walk away from the project with a very good understanding of how electrical chemistry works. A couple of reasons that our project did not work could have been the current was not strong enough to light the LED or the dough had a resistance too high to have the electric current flow through it. We also could have tested to see if five cells would have produced more energy because we only tested it with four cells.
We changed many parts of our batteries during this project to see if we could get a LED to light up. In our playdough, we first tried adding more cells because it does not matter how large each cell is, it will still have the same amount of potential energy. We did this to see if we could get a higher voltage out of the dough which we were able to accomplish. The second thing we tested with the playdough was the materials used for the chemical reaction with the metals. We broke the dough into four pieces; the control, the one with more lemon juice, the one with more salt, the one with equal parts of lemon juice and salt. We thought if we added more lemon juice it would decrease the resistance the dough had on the current because the dough was more of a slime than it was a moldable dough. When we added more citric acid (C6H8O7), there was more citric acid to dissolve in water and this allowed for more hydrogen dissociates from the rest of the acid to form the ions H+ and C6H7O7-. These ions allowed more current to be able to run through the dough making it a more efficient battery. We were able to to increase the voltage of the battery from 0.64v to 0.8v. This still was not enough to power a LED, but we were closer to a working battery. We thought if we added more salt (NaCl) to our dough we could increase the amount ions in the dough because this would allow it to conduct a higher voltage and current. We were able to produce a higher voltage (0.64v to 0.8v) because we added more salt than there was lemon juice already inside the dough. Since we got positive results from both of our tests we thought by adding equal parts of lemon juice and salt to the third test ball would increase the voltage and current enough to light a LED. This made our playdough less efficient than before because the salt ions were reacting with citric acid ions to cause a double displacement reaction, which directly decreased the amount of ions in our solution, which which led to a decreased efficiency of the dough. The ions in the salt Na+ and Cl- where combining with to ions in the citric acid H+ and C6H7O7- to form HCL and NaC6H7O7, this means that very a little electric current was being produced by the reaction on the anode and cathode. We also thought that adding both lemon juice and salt to the gatorade battery would make it more efficient. Like the electric playdough, when we added the salt and lemon juice it made the battery less efficient for the same reasons that it made the electric play dough less efficient. We also thought that switching zinc out with magnesium would cause the battery to be more efficient because magnesium is farther away from copper on the reactivity series than zinc. This allows for a larger reduction reaction and a faster current which we thought could help us power our LED. When we did this it caused tremendous improvement in both of our batteries.
Our energy was moved from the electrons in the magnesium wanting to move to another metal that was lower on the reactivity series. This meant that the magnesium the first reacted with the citric acid (playdough) or electrolytes (gatorade). The oxidation reaction allowed for the energy to flow to where the reduction reaction took place (copper strip), after the reduction reaction the energy is able to flow through wires to the LED. Theoretically our first battery, lemon juice playdough with copper and zinc, should have worked because the copper have a half reaction of 0.337v and zinc has a half reaction of -0.763v. When one subtracts the anode from the cathode, you should get I.337-(-.763)I= 1.1v. In reality, we got 0.64v, which means we lost 0.46v, the energy could have been lost due to electrical resistance in the playdough. When we tested the battery that used magnesium and copper, we had lost a large portion of the potential energy. Copper has a half reaction of .337v and magnesium has a half reaction of -2.37v which means that when one subtracts the anode from the cathode you should get I.337-(-2.37)I=2.707v. We should have had enough energy to power a LED, but the battery was not able to power a LED, this again can be due to the resistance the dough had on the electrical current.
In the end, we were never able to get either battery to work, but we were able to walk away from the project with a very good understanding of how electrical chemistry works. A couple of reasons that our project did not work could have been the current was not strong enough to light the LED or the dough had a resistance too high to have the electric current flow through it. We also could have tested to see if five cells would have produced more energy because we only tested it with four cells.
Reflection
One peak in this project was that I learned a lot while working on this project. Through our many trials we gained an in-depth understanding of how electrochemistry worked. Another peak in this project was that I was very conscientious of my learning. This was because I would asked questions to my group members and teacher. If my group members did not know the answer and my teacher was busy I would research the answer myself.
One pit in this project was that my group did not communicate well with each other. We never did a good job a telling each other who needed to bring in different material for the experiments . Another pit in this project was that I was not too excited about the project so I felt that I was not bringing as many ideas that I could have for my group.
One pit in this project was that my group did not communicate well with each other. We never did a good job a telling each other who needed to bring in different material for the experiments . Another pit in this project was that I was not too excited about the project so I felt that I was not bringing as many ideas that I could have for my group.