-Kyle & Tamra
We decided to plate a stainless steel pocket knife with copper.
First we washed all the equipment that we required for this experiment, we washed:
- Three 1L beakers with water and soap
- Copper strip with vinegar and salt
- Stainless steel knife with a water, HCl, HNO3 and FeCl3 solution
Distilled water, Muriatic acid (HCl) , Nitric acid, Iron Chloride
This is the mixture of acids and bases to clean the knife. The clean copper and knife also.
We created our copper sulfate pentahydrate soluton then connected our copper strip to the positive end of a three volt circuit and connected the knife to the negative end of the circuit. We then placed both metals into the solution and agitated the water while we waited.
This is the creation of the solution and the connections of the circuit.
This is the plating process.
This is the end product of trial 1 and trial 2 with the same solution, just different metals (stainless steal knife and a Canadian nickel).
Why we Took on the Study and What We Expected
We choose to do this experiment because we wanted to do something different than the rest of the class. We also thought it would be a good challenge for us.
We were not expecting for it to work the first time due to all the variables but overall we hoped that the knife blade would be completely plated with a strong and thick layer of copper.
Considering it was our first attempt at plating we were happily surprised to see that it worked after the first try. We believe the key to this experiment was the cleaning process. We worked really hard to clean all the beakers and reactants before the experiment. It seemed to work very well.
We continued in our experiment of copper plating to test what we could do with the solution. In doing this we used a smaller volume of copper solution, we used a warmer copper solution and a higher voltage (4.5). This resulted in a faster plating but the final plate was thinner than the first. If we had more time we would test each of those variables individually to find out what effect they have on the experiment but we simply didn't have the necessary time to do this thoroughly.
When we were using our smallest beaker (80 mL) we expected it to work faster due to the variables we changed but we were concerned the plating wasn't going to be as solid as doing the experiment with a slower progress. To our surprise after leaving the nickel in the solution for about 10 minutes we had a solid plate which even with scrubbing stayed strongly attached to the nickel's surface with only a few very small p=specs chipping off the nickel surface.
When using the larger of the 2 beakers (200 mL), because of the cooler solution - in relation to the smaller beaker - we expected a slower plating process and a thinner plate but we expected it to be stronger than when using the 80mL beaker. After leaving the nickel in the solution or about 10 minutes we took it out and scrubbed it. We found that the plate wasn't as thin as we expected it to be and it was still pretty strong.
Once we played with the solution and technique a bit, we decided to try something else. We were told that if sugar was added the plate would be shinier than a plate with just the copper solution. We tried this with a quarter in a warm solution in the medium beaker. After about 10 minutes in this solution we had a pretty solid plate which did seem a lot cleaner than the regular solution plating on the nickel. It seemed to be a little bit nicer than a quick polish on the nickel.
This is the smallest beaker that we tried.
The nickel is on the left and the quarter is on the right. You can see the difference in the colour on the alligator clip due to the sugar added to the solution (tip) compared to the regular solution (tip).
Problems We Encountered
We didn't have too many problems, though we were expecting many. We were anticipating hat the plating method we originally used would not work, we assumed we would have to adjust the concentration, the voltage or have a problem with the surface we wanted to plate. Although, to our surprise our original solution voltage and plating surface and first attempt worked extremely well.
After using our main solution a couple times (from the1L beaker) we had some problems with it, the colouring seemed off when we were reheating the solution as a warmer solution works better. It seemed we had burned the separated copper sulfate. We ended up discarding that solution and trying to make our own concentration (in the smaller beakers) also to our surprise both of these solutions also worked and pretty well.
Its hard to tell but the separated copper sulfate turned a pale beige colour, when we mixed it in the solution became a strong teal colour