Making An Alloy

Eamon Barkhordarian 6/22/09

Making an Alloy Lab Purpose: In this lab, the copper of a penny will be used to make an alloy with the element zinc. Materials: – – – – – – – – – – – –

Three pennies: two pre 1982 and one post 1982 Zinc material 1M zinc chloride solution Ring stand with 2 iron rings Wire gauze Beaker tongs (to handle watch glass) Crucible tongs (to handle pennies) (1) 250 ml beaker (2) 100 ml beakers Watch glass Laboratory burner Striker

Questions: 1. a. The three coins untreated were almost completely similar to each other. The pre

1982 pennies were a little older and darker someone could assume by looking at them, and the post 1982 pennies looked a little shinier. But overall the size and color of the three pennies were pretty much was on par. When the two pre 1982 pennies were heated in zinc chloride solution only, the main difference was that their color transformed from a bronze color to a very silver color. The size between the three pennies was the same, but the color of the pre 1982 pennies was silver and the post 1982 pennies were bronze. When one of the two pre 1982 pennies was then heated in the burner flame, it turned a gold-ish color. I believe the sizes between the three pennies were the same, but the colors were gold, silver, and bronze. b. The two treated coins look like the metals of their color. Originally the pre 1982 pennies were bronze, but after being heated to the zinc chloride solution, it turned silver. It made it seems as though the penny actually was a silver penny. After being heated in the burner flame after being treated in the zinc chloride solution, the penny took a gold color, and took like a gold penny. 2. a. I believe we were causing chemical changes over physical changes to the pennies.

Chemical changes are atom rearrangements such as burning, rusting, corrosion, or chemically mixing. Physical changes are determined by change of color, shape, or appearance. Because we were burning the penny in the burner flame we were corroding the penny. We weren’t inflicting any physical damage. b. I would disagree with the person. As much as it might LOOK like silver or gold, it still is not we did not create any new metals in this lab, we just changed its color by putting it in solutions and heating it in a burner flame. By using common sense, nothing new can be created. If we only started off with copper and zinc, obviously we won’t end up with gold, otherwise everybody would be doing it.

Eamon Barkhordarian 6/22/09

3. a. An alloy is a substance made by melting two or more elements together, at least

one of them a metal. b. I think we created bronze or brass when he heated the treated penny in the burner flame. They are similar but there are different amounts of copper and zinc though the mixture is heterogeneous. 4. a. The class was matter was solid before treating the penny and heating it. b. The class was matter was solid after treating the penny and heating it. 5. 2 practical uses a. Regardless of the color change in the pennies, we learned that no new precious material was created in this lab. b. This lab helped us understand the concept of creating an alloy 6. a. I believe the copper atoms were rearranged due to corrosion and the mixture in the zinc solution. This created a color change. b. I believe the pennies could be converted back to normal coins if instead of being mixed into a zinc solution, they get mixed into a copper solution.