Aim:
Generate energy using an electrochemical cell.
Equipment:
Zinc metal
Zinc Nitrate solution
Copper metal
Copper nitrate solution
Potassium nitrate solution
Paper towel + Tape
3 beakers (We used two 250ml and one 150ml)
Voltmeter
Iron wool
Method:
- Gather the equipment. You have no experiment without equipment!
- Roll up the paper towel and tape it in place. This acts as our salt bridge
- Taking your smaller beaker, place your salt bridge inside. Place some potassium nitrate in the same beaker and wait for it to soak.
- While it's soaking, clean off the top few layers of the metals and place one of them into each of the larger beakers.
- Connect the voltmeter to the two pieces of metal.
- With the zinc metal, put in a bunch of zinc nitrate (I'm not exactly sure how much.) Do the same with the copper.
- Finally, place in your soaked salt bridge, making sure it does not accidentally touch the metals.
- Record the results.
Results:
We managed to generate about 0.8 volts of energy, our highest being around 0.902 volts. In theory, it should've been 1.101 volts, but we'll go over that later.
Discussion:
Right. Now to the juicy stuff. What the heck is happening? Well, in short, electrons. In this cell, there are two things that can happen in each beaker. The zinc metal, the Zn, has 2 electrons in its outer shell. It doesn't want that. So, it can give away its two electrons and become Zn²⁺ or the zinc solution, the Zn²⁺ we have in the beaker, can gain 2 electrons and become zinc metal. The same can happen in the copper beaker too. Now, because both movements can't happen at the same time and zinc is more reactive than copper, so the metal is going to lose electrons rather than the zinc ions gaining any. The voltmeter is tracking this movement. This means our copper ions are going to be gaining electrons and becoming copper. If we had left the cell for a g e s we would've seen more copper metal in the beaker than what we began with.
But... we had a potassium-nitrate-soaked-paper towel connecting the beakers? What? As we know, the paper was soaked in K⁺NO₃⁻ and that there's a bunch of electrons leaving the Zn moving into the Cu. The movement of electrons is going to cause an imbalance. There's going to be a bunch of negative charges with the copper and a bunch of positive charges with the zinc. Nature likes to be balanced. So nature would implode if this was imbalanced (I'm kidding. I think.). So it's the salt bridge's job to balance this, make it all even and stuff.
While all of this is happening, we generated around 0.882 volts. It tended to fluctuate a lot but my clearest image is 0.882 so we're going to go with that.
Evaluation:
Nothing really... went wrong during this experiment. Obviously, we didn't do it to the exact year 13 standard but that's difficult to do for year 10 students. Next time, I'd want to learn more about why the voltage was lower than it's potential. As previously stated, in theory, it should have been about 1.101 volts. This is because the cell potential of zinc is 0.762 V and the cell potential of copper is 0.339 V. When added together you get 1.101 V. But we got less than that. And I think that it has something to do with the concentration of our chemicals, the resistance given by the salt bridge, and how much we cleaned the metal.
Discussion:
Right. Now to the juicy stuff. What the heck is happening? Well, in short, electrons. In this cell, there are two things that can happen in each beaker. The zinc metal, the Zn, has 2 electrons in its outer shell. It doesn't want that. So, it can give away its two electrons and become Zn²⁺ or the zinc solution, the Zn²⁺ we have in the beaker, can gain 2 electrons and become zinc metal. The same can happen in the copper beaker too. Now, because both movements can't happen at the same time and zinc is more reactive than copper, so the metal is going to lose electrons rather than the zinc ions gaining any. The voltmeter is tracking this movement. This means our copper ions are going to be gaining electrons and becoming copper. If we had left the cell for a g e s we would've seen more copper metal in the beaker than what we began with. But... we had a potassium-nitrate-soaked-paper towel connecting the beakers? What? As we know, the paper was soaked in K⁺NO₃⁻ and that there's a bunch of electrons leaving the Zn moving into the Cu. The movement of electrons is going to cause an imbalance. There's going to be a bunch of negative charges with the copper and a bunch of positive charges with the zinc. Nature likes to be balanced. So nature would implode if this was imbalanced (I'm kidding. I think.). So it's the salt bridge's job to balance this, make it all even and stuff.
While all of this is happening, we generated around 0.882 volts. It tended to fluctuate a lot but my clearest image is 0.882 so we're going to go with that.Evaluation:
Nothing really... went wrong during this experiment. Obviously, we didn't do it to the exact year 13 standard but that's difficult to do for year 10 students. Next time, I'd want to learn more about why the voltage was lower than it's potential. As previously stated, in theory, it should have been about 1.101 volts. This is because the cell potential of zinc is 0.762 V and the cell potential of copper is 0.339 V. When added together you get 1.101 V. But we got less than that. And I think that it has something to do with the concentration of our chemicals, the resistance given by the salt bridge, and how much we cleaned the metal.
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