semi off-topic: how to clean ferrichloride stains

The cat? How about a belt sander? ;-)

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Michael A. Terrell
Central Florida

I don't suppose that you would consider trying to analyze the impact of sodium bismuthate and sodium bisulfite on the ferrous chloride / ferric chloride / cuprous chloride / cupric chloride / ferric hydroxide solutions.

Yes there is usually all those species and more when ferric chloride is used as a copper echant.

You must mean something else other than sodium bismuthate for a reducing agent. It's a very strong oxidizing agent. See:

Maybe you're thinking of something like sodium dithionite.

The interesting thing about mixed oxidation state Fe/Cu complexes is, they are indeed quite mixed! For instance, on mixing Fe(II) and Cu(II) chloride solutions, you would not expect any reaction because Cu(II) is not strong enough to oxidize Fe(II) very far. But a dark complex occurs, containing Fe(II), Fe(III), Cu(I) and Cu(II).

Likewise, the Cu(I)Cl2(-) ion is colorless in solution and Cu(II)Cl4(2-) is green, but on mixing them, an intensely deep brown complex occurs, possibly containing a mixed ion Cl2-Cu-Cl2-Cu-Cl2 (the middle Cl- ions bridge the Cu's), with each Cu approximately +1.5. When a colorless CuCl2(-) solution is exposed to any small amount of air, it immediately becomes intensely dark. Likewise, when a CuCl4(2-) solution is reduced (by copper metal, for instance), it becomes dark, first dark green and then dark brown.

When the brown complex is diluted significantly, the [Cl-] concentration drops and white CuCl precipitates, leaving a weak blue solution of [Cu(H2O)6](2+) (probably with some Cl- ligands too, but not as many as in the concentrated solution).

For such common elements, these chemistries are not actually very well understood!

Tim

-- Deep Fryer: A very philosophical monk. Website @

Well how about that. I misremember ed after 30 or 40 years.

You have that problem too?

I thought I remembered right, but I looked it up in my old Semimicro Quantitative Analysis book to be sure!

Turns out sodium bismuthate is the reagent used to detect manganese. It can oxidize maganese to permanganate ion, which is the detected by its purple color. One normally thinks of (potassium) permanganate as a powerful oxidizer, but bismuthate can oxidize manganese in a low oxidation state all the way to permanganate.

oxidation

Bleach (hypochlorite) too. In fact, bleach is a suprisingly strong oxidizer, not something you'd expect for off-the-shelf products!

Tim

-- Deep Fryer: A very philosophical monk. Website @

Are you saying that hypochlorite can oxidize manganous to permanganate?

I gave it a try, and under both alkaline and acidic conditions I didn't see any purple color (using Clorox for the hypochlorite). But I did get a definite purple with bismuthate. Is some special condition needed?

By the way, have you noticed that Clorox currently on the store shelves is

6.00%, but I'm sure it used to be 5.25%? Is this a comment on the state of our culture? Things are dirtier now, and need a more powerful bleach?

And, speaking of products available off-the-shelf--hydrogen peroxide in the

35% food grade concentration. That stuff is dangerous.

Furthermore, I noticed that Home Depot is selling gallon jugs of concentrated sulfuric acid as a drain opener!

Ha! Just look at Ace Hardware for all the interesting things you can buy by the gallon ;-)

...Jim Thompson

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|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
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|  Phoenix, Arizona            Voice:(480)460-2350  |             |
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see

Alkaline should do it; manganate (rather than permanganate) may be necessary (i.e. hell ass damn alkaline). Yields suck nard, but it can turn color.

is

of

Heh...who knows.

the

I haven't seen it around, just at random anyway. Another excellent oxidizer for sure, and good for some coordination chemistry (blue peroxychromate, red peroxytitanate, etc.).

I get the red bottle stuff, Liquid Fire, from Ace Hardware. I think they recently reformulated; the stuff I bought last month came sealed in a plastic bag (heh, I wonder if they were having too many accidents..) and is darker in color. I don't have large enough Pyrex glassware (..or balls..) to boil it out, so I use it as-is. Still works fine.

Tim

-- Deep Fryer: A very philosophical monk. Website @

I have started noticing recently.

Oh, Yeah. That is one powerful oxidizer. In pure form it is a bit yellowish as well.