Tait Gu
Block H
Lab Report
The Plan
The plan was to change the color of a normal penny using chemicals and heat. We chose to do this for our lab because we thought it was interesting to see how you could use science to change an everyday item like a penny.
To do this, we used a method that we found from the Internet. This involved creating a mixture of sodium hydroxide and zinc powder (creating sodium zincate) and then heating the penny in it. This would turn the penny into a silver color. After this, we would heat the silver colored penny, turning it into a bright gold color.
Figure 1: The gold colored penny
The Results
· Qualitative Data
Changing the penny into a silver color:
This took a longer time than we had expected. The mixture reacts with the penny to create a new coating around the penny (explained in “Scientific facts and Data in our experiment). The more zinc there was, the faster the coins seemed to react with the mixture.
Changing the silver penny into a golden color:
This was almost an instant effect. It would take about 10 seconds for the coin to heat up and then it would turn go. If you kept the penny in the flame after it turned gold, then the newly formed gold colored coating would be destroyed. Some pennies that had black holes in them from the cleaning would remain to have black holes after the color changing. This could mean that the inside of the penny is not copper so it didn’t change color.
Figure 2: Heating a silver colored penny in a flame. This should change it into a golden color
Table 1: This next table shows the steps, how much time they took, our observations and the science involved in them.
Step / Time / Observations / ScienceCleaning pennies in vinegar / 1 day / Pennis had holes / Our prediction: Vinegar is an acid and leaving the pennies in it allowed the vinegar to destroy some parts of the pennies
Mixing the zinc and the sodium hydoxide / 5 minutes / They did not mix well at first. We needed to heat the base bfore it mixed with the zinc / Science Involved: The heat allowed the zinc and the sodium hydroxide to mix together creating sodium zincate
Mixing the penny into the sodium zincate; turning the penny silver / 10 minutes / Took longer than expected; the more solution there was, the faster the penny would change / Science Involved: A chemical reaction occurs when the sodium hydroxide touches the penny, coating the penny with metallic zinc.
Heating the silver penny in the flame / 1 minute at most / Was very fast; never failed once / Science Involved: The coating of metallic zinc and the original copper coating of the penny mix together under the heat to create a golden colored brass coating
What did you learn about science?
Scientific facts and Data in our experiment
The zinc in the mixture reacts with the heated sodium hydroxide creating a new solution called sodium zincate. This solution is then changed into metallic zinc when touched by the copper coating of a penny. The metallic zinc then coats around the penny giving it a silver color, which is a process called galvanization.
Brass is a mixture of copper and zinc. When heating the penny coated with metallic zinc (solver colored), the zinc coating and the original copper coating react and form the alloy brass. This brass is a bright gold color and coats the penny.
This has helped my understanding of the atomic theory of matter in many ways. The mixture of zinc and sodium hydroxide was an example of how the equations we did in class. We added zinc powder to sodium hydroxide to create a new substance, sodium zincate and rearranged the atoms in the molecules. We also got to create the alloy brass by mixing metallic zinc and copper. This means that brass is a solution of the two.
Figure 3: The penny changing from a silver color to a gold color. The bottom of the penny is still silver. This is the result of the two coats of the penny mixing and forming brass.
In this lab, I learned about alloys and galvanization. An alloy is a solution from two or more elements. In this case, the the elements would be zinc and copper and the alloy would be brass. Galvanization is when you coat zinc around another object, usually iron or steel. The galvanization in our lab would be when the zinc coats the copper penny while mixing the penny in sodium zincate.
Next time I would find a little more information about the lab I plan on doing before I start. This allows me to know ahead if I need materials and what’s going on. I would also record data such as the time it took for the copper coating and zinc coating to form a brass coating. This would allow me to do a better analysis of what’s going on. It could also allow me to improve my experiment if I wanted to do it again.