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Penny lab.

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Presentation on theme: "Penny lab."— Presentation transcript:

1 Penny lab

2 Precautions Follow all lab safety rules Wear goggles and aprons
Make sure your penny is clean and shiny Zinc chloride is corrosive if it falls on your skin – inform the instructor and wash under cold water Do not allow the zinc chloride solution to boil

3 Precautions Granulated zinc is combustible do not add water to it follow teacher instruction to dispose off Use forceps to put and remove pennies from the beaker . Do not drop them in beaker Use tongs to hold the hot beaker rinse the zinc treated penny in in water and pat dry with a paper towel Heat gently on the hot plate over heating will result in penny changing back to a copper color follow teacher instructions for disposal of zinc chloride and zinc wash hands

4 Post 1982 Pre 1982

5 Obtain 3 pre 1982 pennies Use vinegar and salt mixture to clean the pennies followed by cleaning them with steel wool

6 Preparation of "Gold" Pennies
Part 2 Procedure 1. Place ~1 g of granular zinc in an beaker dish on a hot plate. 2. Add ~ 10 ml of 1 M zinc chloride and cover with a watch glass. 3. Bring the solution to a gentle bubbling not boiling . 4. Add a penny, cover and simmer until the penny becomes silvery. Stir it occasionally. 5. Use tongs to remove the penny from the evaporating dish and rinse it with water. Part 3 Rinse in water and pat dry 6. GENTLY heat the penny in a hot plate until it turns to gold. forth while heating. You can ruin your penny by overheating it. 7. Drop the penny in a beaker of water. Remove the penny from the beaker and dry.

7 Post pennies To conserve copper and reduce costs, the penny has been made of 97.5% zinc and 2.5% copper,

8 Brass Zinc Copper 8

9 http://bcs. whfreeman. com/chemcom5e/content/cat_010/CC5e_Main_www

10 An alloy An alloy is a material that contains more than one element and has the characteristic properties of metals. primary ways of modifying the properties of pure metallic elements. As an example, pure gold is extremely soft to use to make jewelry -14 karat gold – an alloy meaning that it is 58 percent gold

11 Alloys Wood’s metal 50% Bi, 25% Pb, 12.5% Sn, 12.5% Cd
Uses - Fuse plugs, automatic sprinklers Yellow brass 67% Cu, 33% Zn uses - Hardware items Steel > 97 % Fe, < 3% C Steel Uses -chain, girders, tools Stainless steel 80.6% Fe, 0.4% C, 18% Cr, 1% Ni ---Tableware Plumber’s solder 67% Pb, 33% Sn -----Soldering joints Sterling silver 92.5% Ag, 7.5% Cu -----Tableware Dental amalgam 70% Ag, 18% Sn, 10% Cu, 2% Hg Dental fillings

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