Metal finishing Q&As since 1989

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Student asks what metal plates the fastest

Hello
My name is Akshey.I study in the 7 grade.This is the first time I am doing electroplating.I am doing it for my science exhibition. In copper plating I would like to know if sodium hydroxide is a catalyst.
my next question is:Which metal gets plated the fastest?

Thanking you

your friend,

Akshey T
student - India
2007

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2007

That's a fairly advanced project and questions for a 7th-grader, Akshey. Good luck with it! Sodium hydroxide is not a catalyst to my knowledge.

Regarding which metal gets plated fastest, it would depend on what you mean by fastest. There are practical limits on how much electricity can be applied without "burning", but these in turn depend on how much agitation can be applied, and some such methods might not apply to certain types of parts and types of plating. Then, too, what constitutes acceptable vs. unacceptable burning? In short, if you define "fastest" that way, I think you quickly hit a dead end, and certainly a topic beyond the reach of a 7th-grader no matter how advanced.

So, I think a better way to rephrase your question would be: "What metal deposits the thickest for a given amount of electricity?" To answer this, you would realize that Faraday's Law of Electrolysis says that a gram molecular weight of metal is deposited by a Faraday of charge. Then you could look up the atomic weights of the metals, divide by their oxidation state when in solution, and see what weight of each metal is deposited by this given amount of electricity. Then you could divide by the density of that metal to arrive at the thickness. This would give you a project that you could approach from knowledge of electrochemical basics rather than one which would take years of practical hands-on plating experience to answer.

I don't know the answer offhand, and bet that most plater's don't :-)

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

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Akshey,
Here is another point of view. A catalyst is a substance that favors or promotes a chemical reaction without directly participating in it. Catalysts are like many elder people, they just want to sit aside and watch the party go on. Sodium and hydroxide ions (constituents of sodium hydroxide) are like young people. They like to party, too active to be left outside a chemical reaction. Chemistry can be fun!

Guillermo Marrufo
Monterrey, NL, Mexico
2007

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2007

Words can be fun, too, Guillermo :-)
Can I be a catalyst for change while sitting aside and watching the party go on?

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

As a matter of fact, Ted, this site and your job is pretty much that. A catalyst for us all to participate and enjoy your "party". It's been so much fun and value. Congratulations!

Guillermo Marrufo
Monterrey, NL, Mexico
2007

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Thanks Guillermo; it's been more fun for me than anyone.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2007

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If you mean, most weight of deposit per unit of electricity passed, my answer is gold, from a cyanide solution. It's univalent, each mole of electrons passed results in the deposit of a mole of Au.

If you mean, on a molar basis, it's a toss up between Au and its two upstairs neighbors in the Periodic Table - Ag, and Cu. Both (Cu from a cyanide solution only) exist in a univalent state in the electrolyte.

Most other metals that I can think of that are plated are divalent in the electrolyte.

Dave Wichern
Consultant - The Bronx, New York
2007