Electrolytic Dissolution of Copper Metal

plastic plate with sodium polyacrylate solution and electrolytic set up

Looking for an easy, hands-on experiment to use in your classroom at the beginning of the school year? In the June, 2013 issue of the Journal of Chemical Education, Isao Ikemoto and Kouichi Saitou describe a simple experiment to demonstrate the electrolytic dissolution of copper ions from a copper electrode. This experiment can be conducted using only items that are easily obtained around the home or in grocery stores.

In short, copper wires are attached to the opposite terminals of a 9V battery. The copper wires are submerged in gel comprised of sodium polyacrylate collected from disposable diapers. Electrons are removed from the copper wire attached to the positive terminal of the battery, forming copper ion:

If ammonia is added to this copper wire, the copper ion produced forms a deep blue copper-ammonia complex:

The electrons removed from the copper wire on the positive terminal travel through the battery to the copper wire attached to the negative battery terminal. The electrons on this second copper wire contact water in the gel solution, reducing the water to hydroxide ion and hydrogen gas:

Ikemoto and Saitou report that, given sufficient time, the copper-ammonia complex produced at the wire attached to the positive battery terminal will migrate to the wire attached to the negative battery terminal. When this occurs, the copper ion is reduced back to copper metal:

In the video below, you can view how to carry out this experiment. When I conducted the experiment, I didn’t wait for the copper complex to migrate to the wire at the negative battery terminal to be reduced. Rather, I decided to test the identity of the gas produced at the negative battery terminal.

 

 

Ikemoto and Saitou describe how to carry out this experiment as a classroom demonstration. However, this process is so easy to carry out it makes me wonder if students could conduct this experiment on their own as a hands-on lesson. I’d like to hear from any of you if you present this lesson in your classroom – either as a demonstration or a hands-on experiment.

Collection: 

NGSS

Planning and carrying out investigations in 9-12 builds on K-8 experiences and progresses to include investigations that provide evidence for and test conceptual, mathematical, physical, and empirical models.

Summary:

Planning and carrying out investigations in 9-12 builds on K-8 experiences and progresses to include investigations that provide evidence for and test conceptual, mathematical, physical, and empirical models. Plan and conduct an investigation individually and collaboratively to produce data to serve as the basis for evidence, and in the design: decide on types, how much, and accuracy of data needed to produce reliable measurements and consider limitations on the precision of the data (e.g., number of trials, cost, risk, time), and refine the design accordingly.

Assessment Boundary:
Clarification:

Students who demonstrate understanding can design, build, and refine a device that works within given constraints to convert one form of energy into another form of energy. 

*More information about all DCI for HS-PS3 can be found at 

Summary:

Students who demonstrate understanding can design, build, and refine a device that works within given constraints to convert one form of energy into another form of energy. 

Assessment Boundary:

Assessment for quantitative evaluations is limited to total output for a given input. Assessment is limited to devices constructed with materials provided to students.

Clarification:

Emphasis is on both qualitative and quantitative evaluations of devices. Examples of devices could include Rube Goldberg devices, wind turbines, solar cells, solar ovens, and generators. Examples of constraints could include use of renewable energy forms and efficiency.

Join the conversation.

Comments 2

Deanna Cullen's picture
Deanna Cullen | Wed, 11/06/2013 - 11:37

I used this activity with my AP students during National Chemistry Week. They loved it. We talked through it and discussed, but I will try to create a written assignment to go with it for next time.

The video makes this activity seem less intinidating. Thanks for your work!

GREGORY RUSHTON's picture
GREGORY RUSHTON | Sat, 02/22/2014 - 08:42

just did this yesterday with some AP chem kids in Fulton County here in the ATL, LOVED it...so cool, so cool...thanks for sharing, Deanna and Tom!

 

greg