The Effect of Metal Type on the Voltage of a Galvanic Cell

The Experimenter

Researched by Derek L.
2004-05



PURPOSE


The purpose of this experiment was to determine the effect of electrode combinations on the voltage of a galvanic cell.
 

I became interested in this idea when I was listening to my CD player and wondered how the battery made energy for the CD player to use.


The information gained from this experiment would help all wet cell battery users by finding metals with more electrical output. Almost everyone in our society uses these batteries.



HYPOTHESIS


My hypothesis was that a zinc anode and copper cathode would create the most voltage output.


I based my hypothesis on an article in the Hutchison Dictionary of Science that stated, “The first galvanic battery that was made by Luigi Galvani used zinc as a anode and copper as a cathode which still proves to be efficient.”




 EXPERIMENT DESIGN


The constants in this study were:
  • The size of the metal electrode
  • Amount of electrolyte
  • Size of beaker 
  • Voltmeter
  • Temperature

The manipulated variable was the combinations I use as electrodes to create a galvanic cell.

The responding variable was the electrical output.

To measure the responding variable I used a voltmeter to measure the galvanic cell’s electrical potential.




MATERIALS
       

QUANTITY ITEM DESCRIPTION
 1
Voltmeter
1 Glass Beaker
2 Zinc    2cm x 12cm
2 Copper   2cm x 12cm
2 Lead    2cm x 12cm
200ml Copper Nitrate
200ml Zinc Nitrate
200ml Lead Nitrate
3 Porous cups




 PROCEDURES


1. Clean the copper, lead and zinc strips before starting the experiment. Sand with a fine grade sand paper to take off the outside coating.
2. Place 50ml of the matching electrolyte with the metal strip you’re using in the beaker.
3. Take another electrolyte and add 50ml to the porous and add the matching metal.*
4. Attach the voltmeter’s ends to the two metals.
5. Put the porous cup in the beaker.
6. Immediately take volt recordings in mini volts.
7. Repeat steps 2-5 3 times.
8. After conducting all of the experiment clean up all of the mess from conducting the experiment.



*The matching metal like zinc is matched with zinc nitrate.




RESULTS


The original purpose of this experiment was to determine the effect of electrode combinations on the voltage of a galvanic cell.

The results of the experiment were the lead-copper test created the most potential at 481.2 mv. The lead-zinc test created 106.4 mv. The zinc-copper test created 82.3 mv.



See the table and graph below.

Graphs/DerekL.pdf




 CONCLUSION


My hypothesis was that a zinc anode and copper cathode would create the most voltage output.

The results indicate that this hypothesis should be rejected for the lead-copper galvanic cell created more energy.

Because of the results of this experiment, I wonder if using sulfates or carbonates instead of nitrates as electrolytes would change the electrical output. Another thing that could be changed is the temperature. I did this experiment at room temperature (20∞C). You could do it at 0∞C  (freezing) or at about 40∞C, which is like a hot summer day.      

If I were to conduct this project again I would try to use more anode cathode combinations. I would conduct more trials. I would use a voltmeter that was very precise and accurate below one volt. I would repeat the entire experiment, using fresh electrolytes and electrodes. I would also soak the porous cups for a few hours before the experiment.
 

RESEARCH REPORT

Introduction

Galvanic cells play a role in everyday life. We use them as batteries. If a more efficient galvanic battery could be created by using different metals, that would create more energy while conserving precious materials.
Batteries, Electricity and Galvanic Cells
Electricity is used for lighting homes, heating or cooling, transporting like some trains or elevators, communication like e-mail or telephones, entertainment like music players or gaming devices, and manufacturing which could be the biggest user of all because they use electricity for every piece of machinery and lighting. The sources that this energy comes from are mainly giant generators using steam to power them. The second largest place where this energy comes from are batteries. There are a few places where it comes from wind turbines or solar panels. Wind turbines are still somewhat in testing.

One of the sources that electricity comes from are batteries. Batteries may have one or more cells. Batteries usually have two solid parts called electrodes. There is a positive electrode and a negative electrode. In most batteries the positive is a carbon rod running down the middle of the battery. The negative is the zinc casing. The third part is some type of chemical paste or liquid, which is called an electrolyte. To work the battery is connected to a circuit. The current flows through the carbon rod. Then the current flows back into the negative terminal (the bottom of the battery). The chemicals change while the battery is being used and it is also becoming weaker and running down. Alkaline batteries use a different electrolyte so they can last longer. Rechargeable batteries recharge by reversing the discharge of energy to restore the battery chemically There are many different types of batteries. To name a few there are the simple voltaic cell, the modern dry cell, lead acid battery, nickel cadmium battery, special purpose and experimental batteries, fuel cells, nuclear and solar batteries.

As early as 200 B.C. primitive batteries were being used in Iraq and Egypt. In 1748 Benjamin Franklin coined the term battery. In 1780-1786 Luigi Galvani demonstrated what we now know as the electrical basis of nerve impulses and provided the cornerstone of research for later inventors like Volta. The 1800’s were when Volta created batteries with dissimilar metals and chemical reactions. In 1836 John F.Daniel invented the Daniel Cell that used two electrolytes. This battery was safer than the Volta cell. In 1839-1842 William Grove developed the first fuel cell. In 1859 The French inventor, Gaston Plante developed the first practical storage lead-acid battery that could be recharged. This type of battery is primarily used in cars today. In 1866 French engineer Georges Leclache patented the carbon-zinc wet cell battery. In 1881 J.A. Theubaut patented the first battery with both negative electrode and the porous pot placed in a zinc cup. Carl Gassner invented the first commercially successful dry cell battery. In 1899 Waldmar Jungner invented the first nickel-cadmium rechargeable battery. Batteries create electrical flow but use chemical reactions to create the flow of electrons.

Galvanic cells are used in a process called galvanizing which is the process of coating a metal with another to prevent rusting or corrosion. Galvanized iron is prepared by either dipping iron into molten zinc, or by a method of electroplating. The galvanic cell was named after Luigi Galvani. It has two metals, which were connected with electrolyte, which forms a salt bridge between metals. 1780 Galvani discovered when two different metals were connected with two ends of the same frog leg nerve the frog leg would contract. This is called animal electricity. This experiment paved the way for all batteries to come.
Metals

Lead

Lead is a very poisonous metal. In fact the Ancient Romans made water pipes with lead, so unfortunately many people died from water poisoning. They used lead because it’s corrosion resistant. We now use lead to line tanks filled with corrosive liquids like sulfuric acid. Lead is used for shields against X-ray and gamma ray radiation because of it’s density. Lead is seldom found plain in nature. It’s usually mined. Even though lead is only 0.0013% of the earth’s surface it’s still not known as a rare metal. Lead also forms lots of useful compounds like lead monoxide which is used to make different types of glass like lead crystal or flint glass. Lead silicate is used in the process of making rubber and paints.

Copper

Copper, which was named after the Latin word “cuprum”, which means “from the island of Cyprus”. Copper has been used for at least 11,000 years. Copper is very easy to mine and refine. Methods of extracting copper have been used for over 7,000 years. Copper is the second best in it’s class for electrical flow. Silver is the first for electrical flow.

Zinc

Zinc has been used for over 2,500 years. It wasn’t known as a distinct element until much later. Metallic zinc was first produced in India sometime in the 1400’s. This was done by heating mineral calamine with wool. Zinc was rediscovered by Andreas Sigis Mund Marggraf. In 1746 Andreas created zinc by heating calamine with charcoal. Today one third of zinc is used for galvanization to protect and cover pieces of easily rusting or corroding metals. Zinc is used for this because it doesn’t rust and it’s corrosion resistant. This is done by either by dipping the object in molten zinc or electroplating. Zinc is used in rubber products, cosmetics, paints, printing inks and soap. Zinc chloride is used to protect wood from decay and insects.

Summary

In conclusion batteries are a very important part of our society. That is why if a more efficient galvanic cell would be made it would save precious metals.
 
BIBLIOGRAPHY

“A Galvanic Cell.” 11/3/2004. <http://www.tpub.com/content/doe/h1015v1_109.htm>.

“Battery, and Fuel Cell,” 2003 Britannica.  10/20/04.

“Battery, Electric,” The Columbia Encyclopedia, Sixth Edition 2001 10/27/04

Bellis, Mary “History of the Electric Battery,” Inventors 10/27/04
<http://inventors.about.com/library/invetors/blbattery.htm>.

Brodd, Ralph J  "Battery,” World Book Encyclopedia, 2001.

“Cell, Electrical(or voltaic cell or galvanic cell),” The Hutchinson Dictionary of
Science Helicon Publishing Ltd. 1998
 
Gagnon, Steve. “Copper,” It’s Elemental 11/17/04 <http://education.jlab.org/itselemental/ele029>.

Gagnon, Steve. “Zinc,” It’s Elemental  11/17/04 <http://education.jlab.org/itselemental/ele030>.
 
Gagnon, Steve. “Lead,” It’s Elemental 1/12/05  
          <http://education.jlab.org/itselemental/ele082>.

“Galvanic Cell,” Wikipedia 11/3/04 and 11/10/04

“Galvanizing,”11/3/2004<http://www.factmonster.com/ce6/sci/A0820097.html

Hiemler, Charles H. and Price, Jack.  Focus on Physical Science Columbus, Ohio:
          Merril 1987 page 469

“Inside the Battery,” Young Scientist  Volume 2, Page 55



ACKNOWLEDGEMENTS

I would like to thank the following people for helping make my project possible:
  • My parents for providing me with materials and helping me along the way.
  • Mrs. Helms for helping me get my display board together.
  • Mr. Newkirk for correcting my report and journal dozens of times.

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