An Easy Copper Electroplating Demo for Your Redox Unit

Simple Electroplating Demonstration

My IB seniors are just wrapping up our unit on electrochemistry and redox. This has always been a challenging topic within the IB curriculum. Admittedly, electrochemistry has not ever been my strong suit either, so this year I aimed to strengthen the unit with two additional demonstrations.

Over the summer I ordered a Hofmann apparatus to demonstrate the electrolysis of aqueous solutions. When I tried this demo last fall, I discovered that my glassware was broken. But I'll write about that in a future blog post. Instead, I'll focus on one of the easiest demos I have ever set up. Here is the complete list of equipment and materials:

  • 400 mL beaker
  • 200 mL 1 M CuSO4
  • copper electrode
  • 9V battery
  • A set of alligator clip wires
  • 1 paperclip

Figure 1: Setup of the electroplating system

The 9V battery provides the needed energy to drive the non-spontaneous process in this electrolytic cell (see figure 1). For my demonstration, I connected the battery and let the cell run for about 30 seconds. There isn't much happening visually. But there is a lot going on! The copper ions in solution are reduced, plating the paperclip in a nice coating of relatively pure copper. And the copper electrode is being oxidized, thus replacing the copper ions that plate the paperclip. This keeps the concentration of copper ions in solution at a constant level.

The oxidation half-reaction at the copper anode:

Cu(s) --> Cu 2+ (aq) + 2 e-

The reduction half-reaction at the paperclip cathode:

Cu 2+ (aq) + 2 e- --> Cu (s)

Figure 2 is a picture of the paperclip with a copper coating and the clean shine of the portion of the copper electrode that was submerged in the solution. I only ran the electrolysis for about 30 seconds, but I'd like to try it for a longer time and see how much copper will plate the paperclip. I've got some milligram balances in my room to put to the test to see if the rate of plating can be calculated also. In a scenario where I had a bit more time (and less need to plow through the HL Chemistry curriculum so quickly), I'd like to extend this a bit to have students explore factors that affect the rate of electroplating such as concentration, voltage and temperature of the solution.

Figure 2: Zinc paperclip and copper electrode after 30 seconds of electroplating

Do you have any extensions for this demonstration? Or suggestions for additional ways to show students electrolysis? I would love to hear about your use of this or other demos related to electrochemistry.

 

Collection: 

Safety

General Safety

For Laboratory Work: Please refer to the ACS .  

For Demonstrations: Please refer to the ACS Division of Chemical Education .

Other Safety resources

: Recognize hazards; Assess the risks of hazards; Minimize the risks of hazards; Prepare for emergencies

 

NGSS

Engaging in argument from evidence in 9–12 builds on K–8 experiences and progresses to using appropriate and sufficient evidence and scientific reasoning to defend and critique claims and explanations about natural and designed worlds. Arguments may also come from current scientific or historical episodes in science.

Summary:

Engaging in argument from evidence in 9–12 builds on K–8 experiences and progresses to using appropriate and sufficient evidence and scientific reasoning to defend and critique claims and explanations about natural and designed worlds. Arguments may also come from current scientific or historical episodes in science.
Evaluate the claims, evidence, and reasoning behind currently accepted explanations or solutions to determine the merits of arguments.

Assessment Boundary:
Clarification:

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 construct and revise an explanation for the outcome of a simple chemical reaction based on the outermost electron states of atoms, trends in the periodic table, and knowledge of the patterns of chemical properties.

*More information about all DCI for HS-PS1 can be found at  and further resources at .

Summary:

Students who demonstrate understanding can construct and revise an explanation for the outcome of a simple chemical reaction based on the outermost electron states of atoms, trends in the periodic table, and knowledge of the patterns of chemical properties.

Assessment Boundary:

Assessment is limited to chemical reactions involving main group elements and combustion reactions.

Clarification:

Examples of chemical reactions could include the reaction of sodium and chlorine, of carbon and oxygen, or of carbon and hydrogen.

Join the conversation.

Comments 8

Tom Kuntzleman's picture
Tom Kuntzleman | Mon, 11/21/2016 - 12:39

Love this. And it's so simple! 

Melissa Stewart | Tue, 01/10/2017 - 19:03

Has anyone tried this with less than 1M CuSO4?  Will it still work but just maybe take long for the reaction to occurr?  Thanks!

Lowell Thomson's picture
Lowell Thomson | Thu, 01/12/2017 - 04:03

Hi Melissa,

Thanks for the question. I have not yet tried usinng different concentrations - and in the IB model the students have a full self-designed lab to complete, so I don't often answer these types of questions explicitly with them. Instead, I prefer to say, "There's a great lab idea there!"

I think I might have a student working on this over the next couple months, so I'll report back if there are reasonable results.

Thanks.
Lowell

Michele Richards's picture
Michele Richards | Mon, 06/18/2018 - 05:00

We teach our kids "OIL RIG", but redox reactions can remain an abstract concept. What a cheap and easy way for students to see the results of redox! Thanks for sharing. 

Lowell Thomson's picture
Lowell Thomson | Mon, 06/18/2018 - 08:40

Hi Michele,

Thanks for the positive feedback. Much appreciated. This is an interesting lab in another way also, as the blue color of the solution shouldn't really change much. Copper is being oxidized at the anode, and reduced at the cathode, so the concentration of copper ions in solution remains approximately the same throughout the electroplating.

As for OIL RIG, that's one of the ones I use - along with LEO the lion goes GER. (Loss of Electrons is Oxidation, Gain of Electrons is Reduction.)

Best,
Lowell

Katie Murnion | Mon, 03/18/2019 - 12:41

Hello!

One of my students would like to try this experiment, but with some adaptations. We are looking at Root Killer with copper sulfate instead of lab grade (for budget reasons. Found here: https://www.acehardware.com/departments/plumbing/drain-openers/drain-cle...). My classroom also does not have ventilation other than a window and a fan. I was wondering if there are any safety concerns with inhalation from this project (Can we do this project without a fume hood and will the root killer work as well?).

Thank you! 

David Frohnapfel's picture
David Frohnapfel | Sat, 03/23/2019 - 12:41

I've been sourcing many chemicals locally to save mone compared to large chemical companies. The consumer Root Killer products are as good or better than lab grade copper(II) sulfate which is typically only 99-99.5% pure anyway.  We use the Zep brand Root-Kill for two stoichiometry experiments and 1 spectroscopy experiment and obtain good results.  

Lowell Thomson's picture
Lowell Thomson | Tue, 03/19/2019 - 04:58

Hi Katie,

Thanks for the message.

Honest answer: I think it will be alright (to do without a hood), but our scenarios aren't identical. The electroplating didn't produce any gases when I performed the experiment, so I would expect that to be OK. The one variable is the copper II sulfate source. The bottle lists "inert ingredients" as 1% of the composition, but from what I can tell it doesn't list what those ingredients actually are. I'd suggest trying it yourself first with a small amount just to see if there is anything wierd about the reaction.

I hope that helps - and that your student has a good experiment!

Thanks.
Lowell