Electrochemical Cell (Galvanic cell)

Aim: To create an Electrochemical cell (Galvanic Cell) and measure its voltage.



Equipment: copper metal (Cu), copper nitrate (Cu2+ NO¯3), Zinc metal (Zn), Zinc nitrate (Zn2+ NO¯3), a salt bridge (paper towel and sellotape, Potassium nitrate (K+ NO¯3) 2x 250ml beaker, a 100ml beaker, a voltmeter, metal scrub, wire.





Method:
1. Grab the metal scrub and wipe off the black exterior of both the zinc metal and the copper metal. Then put them in separate 250ml beakers.


2.  Fill up the beaker containing the Copper metal with copper nitrate. Likewise, fill up the beaker containing the Zinc metal with Zinc nitrate.








3. Fill up the 100ml beaker with the Potassium Nitrate.

4. Get a paper towel and repeatedly fold it until it is a long strip. Then wrap sellotape around the strip of paper towel to keep it from loosening up.

5. Bend the strip of paper towel into a U shape and put it into the 100ml beaker until the strip is completely soaked.

6. Connect both metals to the voltmeter.

7. Place one end of your paper towel strip into the beaker containing the Copper nitrate, and place the other end, into the beaker that contains the Zinc nitrate. Note... make sure that your paper towel strip, is not in contact with either of the metals.

8. Done.





Result:

The experiment was a success. Unlike my previous experiment, my group and I managed to get it to work on our first try. And, nothing went wrong during the experiment. As you can see in the photo, we managed to generate 0.895 volts. Although the theoretical voltage of this experiment was 1.104, we tried our best, and that's all that matters.







Discussion 
standard electrode potential table

What is a Galvanic cell?
The type of electrochemical cell that we created in this experiment was called a Galvanic cell. It creates an electrical voltage using oxidation and reduction reactions. To create a Galvanic cell, it requires a salt bridge and two half-cells. Both cells contain a metal (an electrode) and a solution that contains ions of the metal. The only difference between them is that one metal will be more reactive than the other. The metal that is more reactive will lose its electrons, therefore it is an anode. The other half-cell containing the less reactive metal (called a cathode) will gain the electrons. When the more reactive metal loses its electrons, it will form the same ion that the metal is submerged in. The released electrons are transferred to the other half-cell, changing the solution of metal ions back to its metal state. When electrons leave and are gained, it has to be replaced to balance it out. This is where the salt rod comes it. Once the electrons leave the electrode, electrons from the salt rod are drawn in and provide a balance. When we connect a machine in between the two half-cells, the electrons that would usually go straight to the other half-cell goes through the machine and provide it with energy.

What happened in this experiment?
In this experiment, our first half-cell had zinc metal (Zn) as its anode, and zinc nitrate (Zn(NO3)2) as its solution. The second half-cell had copper metal (Cu) as its cathode, and copper nitrate (Cu(NO3)2) as its solution. The zinc metal wants to lose two electrons to become stable, while the copper (Cu) in copper nitrate wants electrons. When zinc metal loses its electrons, it becomes an ion (Zn+2), while the copper ions in copper nitrate take the electrons and become copper metal. After the reaction occurs, there would be extra zinc ions with two positive charges floating around in the zinc nitrate solution, as well as extra nitrates with 3 negative charges floating around the copper nitrate solution. This is when the salt-rod, containing potassium nitrate comes in. Electrons are both drawn in and taken out of the potassium nitrate to neutralise the zinc ions and nitrates.