KellyChemmy : Penny Lab By Izzy, Kelly, and Sasha

Penny Lab

By Kelly Moran, Izzy Berrent, and Sasha Elie

July 8, 2014

Data Table:

Appearance of penny before	Appearance of coin after being boiled in Zinc Chloride	Appearance of penny after being heated on hot plate	Predictions	Results
Luster	Turned lighter and less defined	Became splotchy and multicolored with gold, pink, and black	We predicted the penny would not change that much in the Zinc nitrate because copper is not very reactive.	We can conclude from these observations, that copper is somewhat reactive and reacts with zinc nitrate since it changed quite a bit.
Malleable	Got silver splotches/ stains from the zinc	Also became ashy looking and looked burnt	We predicted that the penny heated on the hot plate would become burnt but not change colors since copper is not very chemically reactive.	Same with burning on the hot plate, we can conclude the copper is reactive since it’s color changed drastically from what a penny would look like normally.

Abstract: What we did (in a nutshell) was boil water with granulated Zinc for a couple minutes and then dropped the pennies inside with tongs and then took the pennies out later. We also placed a penny on the hot plate to see it's reaction to that as well. From this lab, we learned that when coins are mixed and boiled with granulated zinc, it changes it's effects and it's color. This is it's reaction. The purpose of this lab was to test how copper reacted to boiled zinc chloride and how it reacted to being burned as well.

Procedure: We set up three pennies and cleaned them each thoroughly until they were completely clean. We then set aside one of the pennies we had cleaned (which served as the control penny). Then we weighed a sample of granulated zinc which should weigh about 2.0-2.2 grams. Ours weighed 2.14 grams. We then placed it in a 250 mL beaker and used a graduated cylinder to measure 25 ml of 1 M of Zinc Chloride solution. We then added the zinc chloride to the granulated zinc that was in the beaker. Then we covered the beaker and placed it on a hot plate with a watch glass on top. We heated the beaker and waited until it began to bubble inside and then we lowered the temperature to sustain the gentle bubbling. Then we removed the watch glass and removed the two coins and then rinsed them under water and then dried them. We then put one coin on the hot plate at medium heat and turned it every 5 seconds until we saw drastic color changes. Then we rinsed the coin under tap water and recorded our observations. Lastly we compared all the pennies to each other and recorded all the information on our data table.

Results: In our results we found that the penny that was boiled in zinc chloride had reacted to the solution because it had a physical change. The physical change was that it became pinker and less defined. It also got silver stains on the penny as well. We can concluded from this observation that this penny was chemically reactive to zinc chloride and if in it longer may have reacted even more drastically. We also found that the penny that we placed on the hot plate and flipped like bacon back and forth every five seconds became multicolored with splotches of gold, pink, and black. It also turned ashy and looked completely burnt in some areas. We can also conclude from this observation the copper is chemically reactive and physically reactive to heat.

Questions 1-6

1.) The untreated remained the normal color of a penny. The penny heated in zinc chloride solution and became lighter and less defined. The penny that was heated in zinc chloride solution and then turned over a series of times every five seconds on the hot plate became splotchy and had a gold color to it.

2.) Yes because the pennies chemically reacted to the chemicals therefore they must have been a metal.

3.) You could test the metal and record how much it reacts. If it doesn't react a lot then it would be a precious metal.

4.) Some of the copper atoms disappeared. I am not sure where the copper atoms went because the solution (zinc chloride) did not change when we put the pennies in it but the pennies did change. They both turned pinker and lighter and developed stains of silver. It is possible that some of the copper atoms left the penny and went into the zinc chloride solution although the solution did not react to the copper atoms.

5.) Two practical uses for metallic charges include lighting because that involved conducting heat and the copper reacted to heat and another use would be metallic charges in batteries. The copper (plus charge) acts with the zinc (negative charge) in batteries.

6.) I don't think that the treated pennies could ever go back to normal form. It is possible that with a certain solution the pennies could physically change to look normal again but I don't think everything would be the exact same as it was originally.

Here are some pictures from our beautiful lab!