How I Purify?

[KFC]

If You Mix Chloric Acid With Sodium Chloride Then Evaporate It, Is Sodium Chlorate Or Sodium Perchlorate Left Or Not?

[woelen]

What do you think yourself? Think about the reaction which can occur. Chlorate is an oxidizer, especially in acidic environments, chloride can be oxidized (to what?).

 

One of the reaction products will be ClO2, the other will be Cl2. I'll leave it as an exercise for you to try to find out what remains for the largest part after evaporation.

[YT2095]

Woelen, will there even BE a reaction (beyond themal breakdown)? you`ve got Me a little confused now

[woelen]

Sure, there will be a reaction. OK, I'll give them here:

 

Chloric acid is HClO3.

NaCl contains chloride in solution.

So, such a solution contains H(+), Na(+), ClO3(-), Cl(-).

 

Reaction 1: ClO3(-) + 6H(+) + 5Cl(-) --> 3Cl2 + 3H2O

Reaction 2: 5ClO3(-) + 6H(+) + Cl(-) --> 6ClO2 + 3H2O

 

Both reactions occur at the same time.

 

I did the experiment, by adding NaClO3 to HCl, but this is equivalent to adding NaCl to HClO3 (all are ionic in water and then there is no difference).

 

The result is as follows:

 

http://woelen.scheikunde.net/science/chem/exps/clo2/index.html

[Cap'n Refsmmat]

Just a note to woelen, we do have chemistry LaTeX:

 

[ce]ClO3- + 6H+ + 5Cl- -> 3Cl2 + 3H2O[/ce]

[YT2095]

Nice reaction!

 

I`m pleased you said it worked the otherway around too, as I have no Chloric acid to verify this for myself, but I just tried the NaClO3 + HCl and instant yellow liquid, a few bubbles evolved also, and eventualy a strong Chlorine smell in a waft (I made less than a CC total just in case...).

I think I`ll try a Perchlorate next (not today though).

 

Thanks for that

[woelen]

Perchlorate and chloride do not react, not even when the perchlorate is quite concentrated. I have perchloric acid (60%) and I added solid NaCl to this and heated it a little. The NaCl dissolves, but no chlorine at all.

 

Even a solution of KI is not oxidized by perchloric acid in aqueous solution. Perchlorates are remarkably inert in aqueous solution, comparable to sulfate ion. I have not found any soluble reductor, capable of reducing perchlorate in aqueous solution at room temperature in reasonable time.

 

Things totally change, when the temperature is rising (e.g. in pyrotechnics) or when the concentration of the perchloric acid rises to above 70% by weight. Then perchlorate becomes a powerful oxidizer, which even can react explosively.

[YT2095]

dilute HCl (12%) and a tiny amount of KClO3 for some reason seems to attack Copper quite nicely, although at this stage I`m uncertain whether it`s only taking the Oxide off and leaving the copper intact?, I`m actualy after a Cheap PCB etchant, and HCl and Chlorates are 10 a penny!

 

any info on this?

[woelen]

Oh yes, HCl and KClO3 will make a great etching combo, but also a somewhat dangerous one. When the acid is concentrated, then ClO2 is formed and also Cl2 is formed. These fumes are not nice.

 

A safer alternative is to use HCl, with some H2O2 added. This also produces bad fumes, but it cannot make ClO2.

[YT2095]

thnx for that, actualy I`ve had it confirmed this morning also, I left a board in over night using the 12% HCl and a few KClO3 crystals (a spatula full in 150ml). and now there`s patches of board showing where the copper was.

I say patches as it`s not entirely finished yet, the soln is a lovely green color though.

as for Fumes I use a small polycarb box with a lid 4x6" and so it`s not really an issue until it comes to opening time, it also stops any splashes as agitating the liquid helps the reaction along.

[woelen]

YT, try some of this green liquid with your Al-foil experiment from that other thread on electrolysis. You'll love the result. The small amount of KClO3 in it is irrelevant for the Al-experiment, so using this green liquid perfectly works.

[YT2095]

well it was that thread that "Inspired me", I found that a single crystal of KClO3 in the electrolyte cleared the soln to green and removed the blackish copper

 

edit: in addition, how does this KClO3/HCl mixture store? could it be pre-made and stored for use as and when required?

[YT2095]

update <look of stuned disbeleif>

 

the 1`st board I etched took a good 24 hours to complete, which is fine because the stuff`s practical free and I was in no hurry.

I placed another board in the same soln, identical measurements of PCB and copper, then left it in the cuboard to fully exhaust this soln for later use.

I just checked it this morning (9 hours later) and the board is totaly copper free! faster and better than the 1`st time around!?

 

the only difference in variables is that it was dark in there, as opposed to in this room which has a UV light on 24/7.

 

could the Light affect such a reaction?

[woelen]

No, the copper already present makes the reaction much faster. Copper plates dissolve much eaasier in a solution which contains already some copper. Hence, the copper is self-catalyzing. In fact, the solution will become better and better when more copper is in there. You only need to replenish it sometimes by adding a small amount of conc. HCl. KClO3 is not needed anymore. It is important though that the liquid has good air-contact. You get your oxidizer for free, being oxygen from the air.

 

How does this work?

 

Initially you only have HCl in solution. That does not dissolve copper. You add a small amount of oxidizer (in your case KClO3, but H2O2 or even a few ml of chlorine bleach also are OK). This small amount of chlorine, formed from the oxidizer and the HCl is capable of dissolving copper, albeit with difficulty:

 

[ce]Cu + Cl2 + 2Cl^- -> CuCl4^{2-}[/ce]

 

The complex ion, formed in this way, however, is a very good oxidizer for copper. Here appears a very specific piece of copper chemistry. Copper is capable of forming special complexes with multiple oxidation states in one species and this complex breaks down into two complex ions with copper in the +1 oxidation state:

 

[ce]Cu + CuCl4^{2-} -> Cu.CuCl4^{2-} -> 2CuCl2^{-}[/ce]

 

The complex ion CuCl2(-) very easily is oxidized. Even oxygen from the air can easily oxidize this in the presence of acid:

 

[ce]4CuCl2^{-} + O2 + 4H^{+} + 8Cl^{-} --> 4CuCl4^{2-} + 2H2O[/ce]

 

The CuCl4(2-) hence is recycled again and effectively, oxygen is used as oxidizer, and some acid is needed for the oxidizer being effective.

 

It almost seems too good to be true, but still, it is. You only need HCl and oxygen from air to etch copper metal. You only need a small amount of oxidizer (or even better: a copper salt) to get things started.

 

If your liquid turns very dark, then you need to add some acid and you need to let it stand overnight with air contact and then the liquid is replenished again.

 

This very specific reaction only works in the combination HCl/copper. It also works with HBr/copper, but not with other acids, like H2SO4, HNO3 and also not with other metals.

[YT2095]

Thank you!

that certainly goes a long way to explaining my observation!

 

here`s what I have also noticed though, this soln is now a lovely Emerald green in color (almost like a Nickel salt), but when there was a tiny spillage, the liquid went almost Flourescent green/yellow on air exposure and consequent drying, a short while after tiny crystals started to appear, even tualy the little spill was dry and leaft a light blue/green powder, like copper carbonate color.

 

so, now I`m saturating this soln with as much copper as it can dissolve (there`s 160ml of it), and I`ll displace this later to make the Hydroxide as I don`t want any K traces in it, and then I`ll keep this for further experimentation later, saves wasting good Copper

 

and to think, I was prepared to pay nearly 5 pounds for 100gr of ferric chloride etchant!

 

Long Live Chemistry!