Hi,
How many mL of FeCl3.H2O solution is required to just dissolve 1 g of copper in 1 hour? Please provide the chemical and mathematical equations too!
With Regards,
Suhas D.
@Suhas Dinesh: please elaborate your question. I think some information is missing in your question.
Almost impossible to answer, since the time of reaction is strongly depending on the surface of copper and concentration of the FeCl3 solution . A simplified approach would be :
Cu + 2 Fe3+ --> Cu2+ + 2 Fe2+
-> 1eq Cu requires a minimum of 2 eq FeCl3 x H2O
1g Cu = 15,7366 mmol
so you will need about 31,4733 mmol of Fe(III)
in the case of FeCl3 x6 H2O (most common hydrate) [ 270,29] this amounts to:
about 8,507 g dissolved in a appropriate amount of water.
Or 31,47 ml of a 1M solution.
Now the time strongly depends on the Cu surface area and Fe(III) concentration the diffusion -> temp. and so on.
I hope this helps.
Although this reaction can take place easily, as mentioned above, it is not easy to make a solution of ferric chloride to dissolve one g of copper metal in one hour.
Plus that, what is the aim of this reaction? What do you want to do with the final mixture of iron and copper solutions?
Let me elaborate: I want to etch a PCB board containing approximately 2.5 g of copper. I want to know how much of anhydrous FeCl3 is to be dissolved in X mL of water to make an approximate solution.
I read somewhere that it takes 2 Moles of FeCl3 to oxidize 1 Mole of Copper and the solubility of FeCl3 in water is 912 g/L.
Doesn't it translate by simple mathematics that: it takes 12.7624 g of FeCl3 in 13.99 mL of water to oxidize 2.5 g of copper? Is the water content too low? Am I right? I do not know the A B C D of Chemistry, so kindly help me!
In this case its very very simple, you just use a lot more FeCl3 solution than you will need (excess), since the area where you do not want to etch is protected by the screen anyway (i don't know what kind of polymer you use for printing the boards).
So just make a solution of 200 g of FeCl3 x6 H2O in 1 L of water (common etching solution) use this in a bath at room temp. to etch the board.
Check every 5- 10 min so you wont "over etch" your PCB. The solution is reusable and can be used for many PCBs. There is absolutely no need to go with stoichiometry in this case.
Wash the board afterwards really well.
Thanks for the answer Fabian. However, in case I do not want to waste any Ferric Chloride and want to etch the PCB (FR-4 substrate with 2.5 g of Copper on it) really fast, how much FeCl3 and water would I require?
Is it 200g of anhydrous FeCl3 in 1 L of water?
Use the hexahydrate and just put the etching liquid back in the bottle. This way you wont waste much / close to nothing. If you want to do it fast just place your PCB in a plastic or glass vessel, along with about 100 mL of the etching solution.
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