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topic 26556

Need nickel plating Science Project Help


2004

Q. Hi,

I am a parent helping out my 5th grade daughter with her science project named "How to Turn a Penny into a Nickel". She wants to do some rudimentary electroplating and we are looking for about 2 quarts of nickel solution and three or four nickel anodes (about the size in a test kit).  We live in Knoxville, TN. Can anyone recommend where we can locate these materials? Thanks!

Carolyn F [last name deleted for privacy by Editor]
hobbyist - Knoxville, Tennessee, USA


affil. link
"Award Winning Science Fair Projects"
from Abe Books

or

2003

A. You can buy such materials from companies who sell plating kits.

But you might want to rethink whether this would be an appropriate science project for a 5th grader in our environmental age, Carolyn. A manager of a plating shop who gets caught dumping 2 quarts of nickel solution down the drain is probably looking at penitentiary time. Although draconian punishments won't be imposed on a 5th grader and her mom, what are you going to do with the two quarts of nickel plating solution after the project is over? You can't dump it, and it would cost your town over $100 to dispose of if they were to accept it from you in a haz waste collection.

The good news is that you can plate the pennies with zinc from a very dilute (and quite safe) vinegar solution per our "Electroplating: How it Works" FAQ. Zinc is not exactly the same color as nickel, but it's close enough for 5th grade.

Best of luck!

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



June 16, 2020

Q. Dear Sir/Madam,

I am a Masters student. My Project is nickel electroplating onto copper.
For Preparation of the electrolytic solution I took 10 g of Ni powder dissolved in 100 ml conc. HCl and 2 ml of conc. H2O2 were added. After Evaporation it become dry residue and I added distilled water and boric acid. Because the distilled water was so acidic (pH 4) the solution pH was so low and I added some Drops of KOH to become less acidic.

Ni electrodeposition was performed under controlled conditions keeping a current of 3,45 mA and Voltage 2.5. And we also used platinum undissolving anodes. However, finally my samples are not homogeneous; all of them have some holes on the edges.
I wrote some reactions of what happened in the solution but my teacher told me that all of thee equations are nonsense and I am wrong; and he asked me to find out what happened exactly in solution. He told me that we are not taking Cl gas on anode, but on anode we can see clearly some bubbles. Can someone explain why am I wrong?

Please see These Equations:

Ni + 2Cl --> Ni(s)+ Cl2(g)
half reactions 2Cl -> Cl2 +2e
anode 2Cl- + 2e -> Cl2 (gas-bubbles on anode)
2H2O -> O2+ 4H +4e-

on cathode Ni+2e -> Ni (solid deposit on cathode)
4 H2O +4e -> 2H2 (gas) +4 OH-
(bubbles on cathode)
P.S I checked current efficiency and I take 52-55% can you help me to increase this current efficiency ?

I really Need help, if someone can help, I will be grateful. Thanks a lot!!!

with best regards
Sara-elena

sara-elena
- Spain


June 16, 2020 2nd Request

Q. Greetings.
I am a Masters Student and preparing science Project About Nickel electrodeposition.

Stock electrolytic solution containing NiCl2 and H3BO3, was prepared.
Ni electrodeposition was performed under controlled conditions keeping a current 11,51-3,45 mA ,
for 7 hours using 1,5 mL electrolytic solution with the Pt (undissolving) anode at 1 cm from the surface of the Cu cathode. and room temperature 20-25 °C.
The experiments were performed under the same conditions (2.5V)

In our solution we have NiCl2, H2O, H3BO3,
I wrote some reactions About what happened in solution, but my teacher told me that all my equations are nonsense and he gave me time to find out what happened in solution.

Reactions:
Ni 2+ ( aq) +2Cl - (aq-) --> Ni (s)+ Cl2 (g)

2H2O (liquid)-> 2H2 (gas) + O2 (g)

KOH - > K+ + OH-

(K should not reduce on cathode because of low Standard electrode potential (it is between Li-Au)

During the electroplating we can clearly see the gas bubbles on surface of anode and where oxidation happened; also on cathode where reduction happened.

Half reactions:
on anode 2 Cl- + 2 e -> Cl2 (gas-bubbles on anode)
2 H2O (liquid) -> O2 (gas) + 4H+ + 4e-

on cathode Ni2+ + 2e -> Ni (solid deposit on cathode)

4 H2O (liquid) +4e -> 2H2 (gas) +4 OH- (bubbles on cathode)

Can you tell me why and where I am wrong? I really Need help very much! If you can to explain where I made a mistake I will be very grateful.

Looking Forward to your Feedback
with best regardsm

sara-elena [returning]
- Spain


June 2020

A. Hi Elena.
Before I address your questions of the equations and how to increase efficiency, let me start by saying that in conventional nickel electroplating (as practiced in thousands of electroplating shops), nickel anodes are used rather than platinum anodes. Then, if everything is working correctly, the equations are very simple --
At the anode, which is the positive electrode, from which the power supply is "taking electrons":
Ni0 - 2e- --> Ni++
The nickel metal is thus converted into positively charged nickel ions which dissolve into the solution.

At the cathode, which is the negative electrode, to which the power supply is "giving electrons":
Ni++ +2e- --> Ni0
The dissolved nickel ions are thus converted to nickel metal

Ideally, the HCl keeps the pH low, allowing the nickel ions to stay in solution, and the plating solution is basically a mix of hydrogen, chloride, and nickel ions (H+ & Cl- & Ni++) with the chlorine not participating in a reaction at the anode or the cathode. Similarly, the water, which ionizes very little, ideally does does not participate in the reactions at the anode and cathode.

If this ideal situation were maintainable, the 'efficiency' would be 100%. Please see our paper about Faraday's Law. In reality, the efficiency is not quite 100%. In commercial nickel electroplating it might be 95%, but in your case, yes, it might be 52-55%. What happens is that some of the electrons you are pumping to the cathode cannot be satisfied by the available nickel ions (because there is not enough of them, or whatever) but they must be satisfied. So what happens to a small extent is:
2H2O + 2e- --> H2^ + 2OH-
This hydrogen is the gas bubbles that you see on the copper cathode.

When you use a platinum non-dissolving anode instead of a nickel anode, a few things work a bit differently. Since some amount of nickel is being electroplated out of the solution and onto the cathode, and no replacement nickel is going into the solution, the nickel concentration is declining, which causes the efficiency to decline. Further, since there is no nickel dissolving to provide the electrons which the power supply is "stealing" at the anode, something else has to provide those electrons, and your teacher is at least partially wrong in calling your equations nonsense, because the only thing that can then supply those electrons has to be the Oxygen and Chlorine ions forming diatomic gasses :-)
Most of the gas forming on the anode is Oxygen but some of it (the lower the pH, the more) is Chlorine gas. Feel free to search the site for "Wood's Nickel Chlorine Gas" for further info on this.

Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
finishing.com - Pine Beach, New Jersey
Aloha -- an idea worth spreading


June 22, 2020

Q. Dear Mr. Ted Mooney

Thank you so much for the wonderful explanation.
Many things became clear for me.
And I appreciate you very much!!

Would you be so kind to answer one question regarding Nickel electrodeposition?

What will happen in NiCl2 solution without boric Acid during the electroplating (with non dissolving Platinum Anode)?

Looking Forward for your Feedback.
With best regards

sara-elena

sara-elena
- Spain


June 2020

A. Hello again, Sara-Elena.
Boric acid is a buffer which works to keep the pH of the nickel plating solution from varying. Thread 10210 gives a detailed and wonderful explanation of why this is so important. Apparently, without it the pH right at the surface of the cathode would immediately and substantially change because of the
2H2O + 2e- --> H2^ + 2OH-
reaction, and mess things up very badly. NiCl2 simply ionizes into Ni++ + 2Cl-, and the Cl- stays dissolved in the solution, while the Ni++ is converted to Ni0 metal depositing on the cathode.

Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
finishing.com - Pine Beach, New Jersey
Aloha -- an idea worth spreading

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