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Need Help with Electroplating Science Project

2005

Hi,

I am a high school student. I am conducting an electroplating experiment and needed help on a few things. I wasn't sure what my purpose would be at first but I thought about proving Faraday's Law of Electrolysis. Exactly how could I do this. I've tried using 2 different multimeters and measured the amps of the circuit but the digital multimeter says its too much and the other says its only 50 mA. ? Can you help me try and prove Faraday's law and give me pointers on how to do it?

Thanks,

Weston B.
student - Texas

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February 23, 2010

Hi, Weston.

Say that you have an electrode made of zinc and an electrode made of copper sitting in some dilute acid, and you attach a piece of wire to the zinc electrode, connect the other end of the wire to the positive side of battery, and then another piece of wire from the negative side of the battery to the copper electrode.

What will happen is that the Zinc, Zn⁰ will ionize as Zn⁺⁺ because the battery is "stealing" electrons from it. These Zn⁺⁺ ions will migrate through the solution towards the copper electrode, at which point the electrons provided by the battery will reduce the Zn⁺⁺ back to Zn⁰ and the zinc will plate out onto the copper.

Faraday's Law of Electrolysis is both simple and profound. It simply says that, since Zn ionizes as Zn⁺⁺ , if you move two electrons with the battery you will move a molecule. If you move two thousand electrons with the battery, you move a thousand molecules. So the mass you move is proportional to how much electricity flowed.

In full form, Faraday's Law says that 96,485 coulombs (ampere-seconds) will move one gram molecular weight of the metal.

Faraday's Law ties together a lot of things like atomic weight, molecular weight, Avagadro's number, etc. If you can measure the current with a milliammeter, and measure the time, and keep the plating voltage very low so that no electrons are "wasted" liberating water into hydrogen and hydroxide, yes, you can prove Faraday's Law.

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey