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
Cleaning
pennies in
vinegar
Mixing the zinc
and the sodium
hydoxide
Mixing the
penny into the
sodium
zincate;
turning the
penny silver
Heating the
silver penny in
the flame
Time
Observations
Science
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
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
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.
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
10 minutes
1 minute at
most
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.