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Recycling Copper: Understanding Chemical Reactions (10 Favorites)

LAB in Classification of Reactions, Chemical Change. Last updated April 25, 2019.


Summary

In this lab, students will demonstrate their understanding of writing, balancing, translating, and identifying types of chemical reactions. While doing so, they will learn about the process of recycling copper.

Grade Level

High school

AP Chemistry Curriculum Framework

  • Big Idea 1: The chemical elements are fundamental building materials of matter, and all matter can be understood in terms of arrangements of atoms. These atoms retain their identity in chemical reactions.
    • 1.18 The student is able to apply conservation of atoms to the rearrangement of atoms in various processes.
  • Big Idea 3: Changes in matter involve the rearrangement and/or reorganization of atoms and/or the transfer of electrons.
    • 3.1 Students can translate among macroscopic observations of change, chemical equations, and particle views.
    • 3.2 The student can translate an observed chemical change into a balanced chemical equation and justify the choice of equation type (molecular, ionic, or net ionic) in terms of utility for the given circumstances.

Objectives

By the end of this lab, students should be able to

  • Observe evidence that a chemical change has taken place.
  • Describe reactions by writing word equations and balanced chemical equations.
  • Identify types of reactions taking place.
  • Understand copper is being recycled throughout the experiment.

Chemistry Topics

This lab supports students’ understanding of

  • Indicators of chemical change
  • Classifying chemical reactions
  • Balancing chemical equations

Time

Teacher Preparation: 15 minutes

Lesson: 2 periods (45 min) or 1 block (95 minutes)

Materials

(Per lab group)

  • Small test tube
  • Two 100 mL beakers
  • Test tube rack
  • Glass marking pencil
  • 1.0 M NaOH (3 mL per each group)
  • 1.0 M HCl (3 mL per each group)
  • 1.0 Copper (II) nitrate (3 mL per each group)
  • Stirring rod
  • Aluminum wire (cut to 12 cm)
  • Wire cutters
  • Hot plate
  • Beaker tongs
  • Test tube tongs

Safety

  • Always wear safety goggles when handling chemicals in the lab.
  • Students should wash their hands thoroughly before leaving the lab.
  • When students complete the lab, instruct them how to clean up their materials and dispose of any chemicals.
  • When working with acids and bases, if any solution gets on your skin immediately rinse the area with water.
  • Consult the SDS for HCl and the SDS for NaOH for additional information.

Teacher Notes

  • Instead of having students mark the test tube at 1 cm marks, you may prefer your students to measure 3 mL of each solution.
  • This activity works best if students stop after Part 1 and complete the questions specific to the reaction completed before moving on to Part 2, and so on.
  • I require students to show me their work from Part 1 before moving on to Part 2 (and etc.) so I can check for misconceptions and/or provide guidance when necessary.
  • I personally do not tell students what they are going to see or find while performing the lab. I do, however, point out that a product will have to be the reactant in the next part of the lab. This clarification is helpful for students to understand.
    • Part 1: Copper (II) nitrate is blue and sodium hydroxide is clear. When added together, a precipitate will form and become more electric blue.
    • Part 2: The precipitate, copper (II) hydroxide, is heated until it turns black forming a new solid, copper (II) oxide.
    • Part 3: A clear solution of hydrochloric acid will be added to the copper (II) hydroxide, and upon stirring should turn back to a blue solution. If it does not turn blue, have students add more hydrochloric acid until it does.
    • Part 4: Aluminum wire will be added to the blue solution. Hydrogen gas will be produced (bubbles will be visible). A single replacement reaction will also occur, allowing copper solid to be formed.
  • Students will need to have experience with the following concepts in order to complete this lab:
  1. Writing formulas for ionic and covalent compounds.
  2. Balancing chemical equations.
  3. Identifying the type of reaction as synthesis, decomposition, single replacement, double replacement, or combustion.
  • When students “translate” the equation into a sentence, I require students to use the terms atoms, units and molecules. For example:

2NaCl(s) → 2Na(s) + Cl2(g)

Two units of solid sodium chloride decompose to form two atoms of solid sodium and one molecule of chlorine gas.

Atoms are used to represent an element.
Units are used to represent an ionic compound.
Molecules are used to represent a covalent compound.

  • In order for students to see what the final product will look like, I have a demo set aside so they can see what will happen in 20-30 minutes.
  • Students may also view this copper recycling lab on YouTube, or you may show this to them to review what actually happened.
  • This lab was intended for a 90 minute block. If planning on completing over two days, consider having students do the actual lab work on day 1 and focus on translating, writing, balancing, identifying, etc. on day 2.
  • This laboratory experience could also be used to introduce limiting and excess reactants as an extension. In the final step of the lab, aluminum metal is added to the test tube resulting in two different reactions. The reaction with excess hydrochloric acid added in the previous step produces hydrogen gas. The second reaction between the excess reactant, aluminum, and the limiting reactant, copper (II) hydroxide, produces elemental copper. This reaction will be complete when the solution turns from blue to clear and elemental copper has collected on the aluminum wire.
  • For clean up, I have students empty their waste in a large filtering system (filter with Erlenmeyer flask). Add 1.0 M NaOH slowly while stirring until all the copper has precipitated as the hydroxide. Remove the precipitate and dry, then put into the trash. Slowly, while stirring, add all the waste HCl solution to the filtrate. Then adjust the pH of this mixture between 5 and 9 by adding 1.0 M acid or base, as needed. Pour the neutralized mixture down the drain. Disposal according to Flinn Method #26b.
  • As an extension, students could draw a flow chart to illustrate the transformations of copper throughout the lab.

Cross-Disciplinary Extensions

Connect to Reading
Students could read an excerpt from The Disappearing Spoon by Sam Kean. Pages 167-169 of Chapter 10"Take Two Elements, Call Me in the Morning," focuses on the importance of copper in everyday life.

For the Student

Background

As early as 4500 BCE, copper was one of the first metals to be isolated, due to the ease of separating it from its ores. Copper is a ductile, malleable metal and is easily pounded and/or drawn into various shapes for use as wire, ornaments, and implements of various types. Alloys of copper (bronze, brass) were discovered quite early in history and used in international trade. In modern times, we take for granted the supply of metals, as well as plastics and medicines. We have come to depend on the chemical industry to provide us with the materials needed for everyday life.

Unfortunately, the supply of these materials is limited, and as the population and demand continues to grow the consumption of these materials is increasing. Therefore, we need to develop methods for chemical processing that are both chemically and environmentally efficient.

Reuse and recycle are becoming essential ways to manage resources. In this laboratory, we can learn about sustainability with the starting color and appearance being regenerated at the end of the experiment.

Purpose

The purpose of this lab is to perform a sequence of chemical reactions illustrating the properties of copper and its compounds. Copper (II) nitrate will undergo a series of reactions including decomposition, single replacement, and double replacement. At the completion of the lab, elemental copper will be produced.

Objectives

  • Observe evidence that a chemical change has taken place.
  • Describe reactions by writing word equations and balanced chemical equations.
  • Identify types of reactions taking place.
  • Understand copper is being recycled throughout the experiment.

Materials

  • Small test tube
  • Two 100 mL beakers
  • Test tube rack
  • Glass marking pencil
  • 3mL of 1.0 M NaOH
  • 3mL of 1.0 M HCl
  • 3mL of 1.0 Copper (II) nitrate
  • Stirring rod
  • Aluminum wire (12 cm)
  • Hot plate
  • Beaker Tongs
  • Test tube tongs

Safety

  • Always wear safety goggles when handling chemicals in the lab.
  • Wash your hands thoroughly before leaving the lab.
  • Follow teacher instructions for clean up and disposal of chemicals.
  • When working with acids and bases, if any solution gets on your skin immediately rinse the area with water.

Procedure

Part 1

  1. Use the lab pencil and ruler to make three marks on the test tube. Each should be 1 cm apart, starting by measuring 1cm from the bottom of the test tube to make the first mark and move toward the top.
  2. Add 1.0M copper (II) nitrate solution to the lowest mark on the test tube.
  3. Add 1.0M sodium hydroxide solution up to the second mark on the test.
  4. Mix the combined solutions with the stirring rod. Rinse the stirring rod thoroughly with water before setting it down on the lab table.

PAUSE AND COMPLETE THE FOLLOWING:

The reaction that took place in Part 1 is as follows:

copper (II) nitrate + sodium hydroxide → copper (II) hydroxide + sodium nitrate

  • Write the balanced chemical equation including states of matter below.Note: copper (II) hydroxide is a solid; all other reactants and products are aqueous.
  • Translate this equation into a sentence:
  • Identify the type of reaction that is taking place:
  • List your observations that indicate a chemical reaction is taking place:
  • What color is the copper solution?

Part 2

  1. Obtain a 100 mL beaker and fill half way with water. Heat until the water boils.
  2. Put the test tube into the water bath. Heat it until no more changes occur. (There should be a distinct color change here…be patient!)

PAUSE AND COMPLETE THE FOLLOWING:

The reaction that took place in Part 2 is as follows:

copper (II) hydroxide → copper (II) oxide + water

  • Write the balanced chemical equation including states of matter below.
    Note: copper (II) hydroxide and copper (II) oxide are solids; water is a liquid.
  • Translate this equation into a sentence:
  • Identify the type of reaction that is taking place.
  • List your observations that indicate a chemical reaction is taking place:
  • What color is the copper (II) oxide solution?

Part 3

  1. Obtain a 100 mL beaker and fill half way with room temperature water.
  2. Using test tube tongs, remove the test tube from the hot water bath. Turn off the hotplate. Cool the test tube and its contents for 2 minutes by placing it in the room temperature water bath that you created in step 1.
  3. Next, add 1.0M hydrochloric acid to the third mark on the test tube.
  4. Mix with stirring rod. Rinse stirring rod with water after using.

PAUSE AND COMPLETE THE FOLLOWING:

The reaction that took place in Part 3 is as follows:

copper (II) oxide + hydrochloric acid → copper (II) chloride + water

  • Write the balanced chemical equation including states of matter below. Note: copper (II) oxide is a solid; hydrochloric acid and copper (II) chloride are aqueous; Water is a liquid.
  • Translate this equation into a sentence.
  • Identify the type of reaction that is taking place.
  • List your observations that indicate a chemical reaction is taking place:
  • What color is the copper (II) chloride solution?

Part 4

  1. Place a 12 cm piece of aluminum wire in the test tube.
  2. Leave the wire in until no reaction is observed. Be patient, this will take time!

PAUSE AND COMPLETE THE FOLLOWING:

There are two reactions taking place in Part 4.
The first reaction that took place in Part 4 is as follows:

copper (II) chloride + aluminum → copper + aluminum chloride

  • Write the balanced chemical equation including states of matter below.
  • Note: Copper (II) chloride and aluminum chloride are aqueous; aluminum and copper are solids.
  • Translate this equation into a sentence.
  • Identify the type of reaction that is taking place.
  • List your observations that indicate a chemical reaction is taking place:
  • What color is the copper?

The second reaction that took place in Part 4 is as follows:

aluminum + hydrochloric acid → hydrogen gas + aluminum chloride

  • Write the balanced chemical equation including states of matter below.
  • Note: Hydrochloric acid and aluminum chloride are aqueous; aluminum is a solid.
  • Translate this equation into a sentence.
  • Identify the type of reaction that is taking place.
  • List your observations that indicate a chemical reaction is taking place:

Part 5

  1. Observe the demo provided by your teacher in order to see the final product.
  2. Place final product in waste container and clean up lab space as directed.