Comparing the Electrical Output of Various Electrolyte



PURPOSE

The purpose of this experiment was to compare the electrical potential of various electrolyte/electrode combinations in a wet-cell battery.

I became interested in this idea when my dad entered a school for H/VAC Technicians.  He taught me how to use a voltmeter.  After that I became more and more interested in batteries.  



The information gained from this experiment could benefit battery producers.  They need to know which electrolyte they should add to a wet-cell battery so that it will give the greatest electrical voltage. 

Electrical Output of Various Electrolyte


HYPOTHESIS

My hypothesis was that the zinc and copper wet-cell battery would produce more electrical voltage. 

I based my hypothesis on the fact that everyday batteries are made of a zinc-copper mix.  This lead me to believe that producers use zinc and copper in the batteries that they produce because they have the best performance compared to other combinations.

EXPERIMENT DESIGN

The constants in this study were:

• Amount of electrolyte

• Size of test tube

• Size of zinc and copper strips

• Number of strips

• Size of wires

• Length of wires

• Voltmeter


The manipulated variable was the electrolyte and electrode combinations I was testing. 

The responding variable was the electrical potential, in volts, of the different liquids I used.   

To measure the responding variable, I used a voltmeter to find the amount of volts the battery produces.   

MATERIALS
        
QUANTITY
ITEM DESCRIPTION
2
copper strip
zinc strip
2
lead strip
2
porous cup
250mLbeaker
150 mL
Zinc Nitrate solution
150 mL
Copper Nitrate solution
150 mL
Lead Nitrate solution
1
voltmeter
1
pair of safety goggles
1
apron
1
pair of gloves
1 sheet
fine-grain sandpaper (220 grit)

 
PROCEDURES

1. Put on rubber gloves, apron, and safety goggles.

2. Clean zinc, copper, and lead strips with fine-grade sandpaper to remove outside coating.

3. Place about 75mL of zinc nitrate solution in a 250mL beaker.  Immerse clean zinc strip in solution.

4. Fill porous cup with about 2 cm of copper nitrate solution.  Immerse clean copper strip in solution.

5. Connect one wire to the zinc metal and the other to the copper metal.  Connect each wire to voltmeter.

6. Lift up and touch porous half-cell to the beaker’s solution to see if the battery is hooked up properly.  The needle should deflect to the positive side of the meter.  Switch the wires if the needle shows a negative deflection.  

7. Place porous cup in beaker and immediately read meter.  Record voltage in table. 

8.  Repeat for 10 trials.

9. Prepare lead half-cell in another beaker by pouring 75mL of lead nitrate solution in 250mL beaker.  Clean copper strip thoroughly and rinse outside of porous cup with distilled water.  Immerse copper cup in lead solution.  Record voltage in notebook for 10 trials.

10. Change porous cups and set up zinc half-cell in porous cup by filling it 2cm with zinc nitrate solution.  Place clean zinc strip in porous cup.  Immerse zinc cell in lead nitrate solution.  Repeat for 10 trials.

11. Clean-up area and wash materials with distilled water.    


RESULTS

The original purpose of this experiment was to compare the electrical potential of various electrolyte/electrode combinations in a wet-cell battery.

 The results of the experiment were that the lead-copper cell had the greatest electrical potential with an average of 483.6 mV.  The zinc-copper cell had the least with an average of 93.8 mV.  The lead-zinc cell was a high second with 421.1 mV.

CONCLUSION

My hypothesis was that the zinc and copper wet-cell battery would produce more electrical voltage.

The results indicate that this hypothesis should be rejected, because the zinc-copper cell has the lowest voltage.  The lead-copper cell performed the best. 

Because of the results of this experiment, I wonder if the temperature of the electrolytes/electrodes would affect the voltage. I wonder if a more concentrated electrolyte would produce more electrical output.  I also can’t help but wonder if the size of the electrodes would affect the voltage it produces.

My findings should be useful to battery producers because my results show that lead-copper produce more voltage than anything else I tested.

If I were to conduct this project again, I would use more combinations of electrolytes and electrodes.  I would also conduct more trials for each combination to receive more reliable results. 


Researched by --- Kevin B


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