Publication No. 11868
Student Laboratory Kit
Materials Included In Kit
Acidified cupric nitrate solution, 0.05 M, Cu(NO3)2, 250 mL
Galvanized (zinc-coated) iron, 2½" x 2½" pieces, 28
Hydrochloric acid solution, 6 M, HCl, 500 mL
Cotton swabs, 28
Masking tape, 4 rolls
Scalpels, disposable, 4
Additional Materials Required
Acrylic sealer (optional)
Graduated cylinder, 50-mL
Hydrochloric acid solution is corrosive to skin and eyes and is moderately toxic by ingestion and inhalation. Acidified cupric nitrate solution is slightly toxic by ingestion and is a skin, eye and mucous membrane irritant. The edges of the galvanized iron are sharp; be careful of cuts and scratches. Wear chemical splash goggles, chemical-resistant gloves and a chemical-resistant apron. Please review current Safety Data Sheets for additional safety, handling and disposal information.
Please consult your current Flinn Scientific Catalog/Reference Manual for general guidelines and specific procedures, and review all federal, state and local regulations that may apply, before proceeding. Neutralize and dispose of the hydrochloric acid solution according to Flinn Suggested Disposal Method #24b. Dispose of the acidified cupric nitrate solution down the drain according to Flinn Suggested Disposal Method #26b.
Correlation to Next Generation Science Standards (NGSS)†
Science & Engineering PracticesAnalyzing and interpreting data
Constructing explanations and designing solutions
Disciplinary Core IdeasMS-PS1.A: Structure and Properties of Matter
MS-PS1.B: Chemical Reactions
HS-PS1.B: Chemical Reactions
MS-PS1-2. Analyze and interpret data on the properties of substances before and after the substances interact to determine if a chemical reaction has occurred.
Fun with Chemistry; Institute for Chemical Education, University of Wisconsin—Madison, 1994.
Holiday fun—combine chemistry and art to design a holiday ornament!
Oxidation–reduction, or redox, reactions are reactions in which electrons are transferred from one element to another. There are two key parts present in every redox reaction—an element that is oxidized and an element that is reduced. Oxidation of an element occurs when the element donates electrons. The net result is that the charge on an oxidized substance increases (e.g., 0 to +2) during a chemical reaction. Reduction of an element occurs when an element accepts electrons. As a result, the charge on a reduced substance decreases (e.g., –1 to –2) during a chemical reaction. Because it is the reduced substance’s charge that is reduced, this is often a convenient way to remember which is the oxidized and which is the reduced species.
Another way to look at a redox reaction is in terms of oxidizing and reducing agents. The substance that accepts electrons in a chemical reaction is the oxidizing agent while the reducing agent is the substance that donates electrons. An easy way to identify the oxidizing and reducing agents in a chemical reaction is to look at the difference in charge on each species between the reactant sand the products. The charge on the reducing agent increases during a chemical reaction—the reducing agent is oxidized. On the other hand, the charge on the oxidizing agent decreases during a chemical reaction—the oxidizing agent is reduced. In general, the reducing agent is oxidized by the oxidizing agent, and the oxidizing agent is reduced by the reducing agent.
Two redox reactions will be performed in this activity. In each case, the transfer of electrons may be followed by looking at the charges. The first reaction involves the oxidation of zinc metal by hydrogen ions.
Zn(s) + 2H+(aq) → Zn2+(aq) + H2(g)
In this reaction, the charge on Zn increases from 0 to +2, while the charge on H is reduced from +1 to 0. Therefore, Zn is oxidized and H is reduced. Since Zn is oxidized, it must have been oxidized by the oxidizing agent which must be H. Since H is reduced, it must have been reduced by the reducing agent which must be Zn. So, in this reaction, Zn is the reducing agent, and H is the oxidizing agent.
The second reaction to be performed in this activity occurs between iron and copper (II) ions. Can you identify the oxidizing agent and the reducing agent in this reaction?
Fe(s) + Cu2+(aq) → Fe2+(aq) + Cu(s)
In this activity, a piece of galvanized iron is used to make an ornament. Galvanized iron is iron coated with a layer of zinc. The zinc protects the iron from rusting. The zinc layer is removed by submerging the galvanized iron in hydrochloric acid. The reaction between zinc and hydrochloric acid generates lots of bubbles from the formation of hydrogen gas.
Zn(s) + 2HCl(aq) → ZnCl2(aq) + H2(g)
Once the zinc layer is removed, the iron surface then reacts with cupric nitrate. As the reaction occurs, copper is plated onto the surface of the iron.
Fe(s) + Cu(NO3)2(aq) → Fe(NO3)2(aq) + Cu(s)
Therefore, everywhere that the zinc layer was first removed and then the iron layer was reacted with cupric ions, the color of the ornament is copper-colored. Everywhere the galvanized iron did not undergo the reaction, it remains the original silver color. By designing a pattern and only allowing part of the pattern to be exposed and undergo the reactions, the exposed part of the pattern will turn copper-colored, while the unexposed part will remain silver-colored. This redox concept can thus be used to create an ornament of creative and original design.
Acidified cupric nitrate solution, 0.05 M, Cu(NO3)2, 25 mL
Galvanized (zinc-coated) iron, 2½" x 2½" piece
Hydrochloric acid solution, 6 M, HCl, 50 mL
Acrylic sealer (optional)
Graduated cylinder, 50-mL
Hydrochloric acid solution is corrosive to skin and eyes and is moderately toxic by ingestion and inhalation. Acidified cupric nitrate solution is slightly toxic by ingestion and is a skin, eye and mucous membrane irritant. The edges of the galvanized iron are sharp; be careful of cuts and scratches. Wear chemical splash goggles, chemical-resistant gloves and a chemical-resistant apron. Wash hands thoroughly with soap and water before leaving the laboratory.