2 ChemCatalystLong ago, early scientists tried to turn ordinary things into gold. This pursuit was called alchemy and the people who engaged in alchemy were called alchemists.Alchemy is the scientific process of trying to turn inexpensive metals like Lead (Pb), Iron (Fe), etc. into gold (Au).
3 ChemCatalystDo you think the Alchemists were successful? Why/Why Not?!?!Today you are going to be an Alchemist!!!You will accomplish this task by turning a piece of metal (penny) with little value into Gold!!!
4 History of the Penny1793–1857: 100% copper 1857–1864: 88% copper, 12% nickel 1864–1942: 95% copper, 5% tin and zinc 1943: zinc-coated steel1944–1946: 95% copper, 5% zinc 1946–1962: 95% copper, 5% tin and zinc 1962–1982: 95% copper, 5% zinc 1982– Now: 97.5% zinc core and 2.5% copper
5 So…The Big Question isCan we turn a penny into gold?
6 You will be…Following a procedure using lab equipment and describing your observations.You must practice HIGH levels ofSAFETYtoday!
7 Lab ActivityPurpose: In this activity you will be transforming a copper penny and discussing what happens.Safety Note: You must wear safety goggles at all times. DANGER! Sodium hydroxide will burn skin, eyes, and clothing.
8 Lab Procedure1. I will place enough zinc filings in a 100 mL beaker to cover the bottom.2. I will carefully add 20 mL of 3M sodium hydroxide to the same beaker.3. A beaker will be placed on a hot plate which has to be set to “4”. If the liquid begins to boil, turn down the hot plate a little.4. You will use tongs to pick up the penny and place it in the beaker.
9 Lab Procedure Cont’d5. Once the penny is coated completely, remove it with the tongs. Make sure your lab partner uses the tongs to hold the hot penny while it is removed.6. Put the hot penny in a beaker, which is half filled with cold tap water. This serves to cool and rise the penny.7. Once the penny has cooled, bring the penny to me at the heating area.
10 Lab Procedure Cont’d8. I will use the tongs to place the penny into the flame of the torch.9. I will hold the penny over the flame until it changes color. Pay attention, it happens quickly (within ten seconds).10. Once the penny cools, I will place it into a cool beaker of water. You may then take it and begin to answer your post lab questions.
11 Some Helpful Tips1.) Flip your penny over in the beaker after one side is coated. (Write down your observations Before, During and After you have rinsed your penny.)2.) Bring your penny to me for “torching”. (Write down your observations after you have torched your penny.)3.) Return to your seat w/ your penny and answer the 4 questions on the back of your lab sheet.
12 What Happened?!?! Nope!!! (sorry… ) Did you make Gold?!?! In the 1st step you coated the penny with Zinc (Zn). (Kind of like “painting” the penny.)In the 2nd step you are heating the penny up so that the Copper (Cu) atoms can mix with the Zinc (Zn) atoms which makes the mixture called Brass!!!
13 Changing the PennyWas changing the penny to Gold a physical or a chemical change?= Physical Change!!!How did you know it was a physical change?Because it was a mixture of the two metals! (Zinc and Copper= Brass)