# Working with ferric chloride hexahydrate **URL:** \ **Category:** Factual Questions\ **Created:** [May 13, 2017, 2:48pm UTC](https://boards.straightdope.com/t/working-with-ferric-chloride-hexahydrate/786535 "2017-05-13T14:48:49Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![Patty\_O\_Furniture](https://avatars.discourse-cdn.com/v4/letter/p/96bed5/32.png) [@Patty\_O\_Furniture](https://boards.straightdope.com/u/Patty_O_Furniture)\ **Post date:** [May 13, 2017, 2:48pm UTC](https://boards.straightdope.com/t/working-with-ferric-chloride-hexahydrate/786535/1 "2017-05-13T14:48:49Z")
I asked somebody to pick up some ferric chloride solution, but what they brought me is FeCl[sub]3[/sub] + 6H[sub]2[/sub]O. I am not exactly sure what I can do with this, or if I can use it to etch a copper-clad circuit board. For one thing, I can’t even get it out of the bottle. It seems to have all solidified into a solid mass at the bottom, with a thin layer of yellowish liquid on the top. And all of that is inside a plastic bag within the bottle. It doesn’t look at all like the dry yellow crystals on the [wiki page](https://en.wikipedia.org/wiki/Iron(III)_chloride). [Here a pic of what I am dealing with](http://pic20.picturetrail.com/VOL1473/5747827/15966180/413343037.jpg). I noticed on the wiki page that the melting point is a mere 37°C. Is it possible it was left in a hot place and melted and then re-solidified into an impenetrable chunk within the bottle? Could I set the bottle in a hot water bath and make the stuff workable again? Thanks in advance to any chemical-science-type people who can provide me with some clues. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [May 13, 2017, 2:57pm UTC](https://boards.straightdope.com/t/working-with-ferric-chloride-hexahydrate/786535/2 "2017-05-13T14:57:39Z")
IANAChemist, but I would guess that this is one of those situations where the two substances exist in a dynamic equilibrium, and that it is impossible, or nearly so, to have a pure sample of one without the other, and that a container labeled as one is indistinguishable in its contents from one labeled as the other. Sort of like carbonic acid vs. aqueous carbon dioxide. That said, I have no idea what the solid mass or yellowish liquid you have are, or whether they’ll work for what you want. ---
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [May 13, 2017, 6:07pm UTC](https://boards.straightdope.com/t/working-with-ferric-chloride-hexahydrate/786535/3 "2017-05-13T18:07:07Z")
There are better and less-messy solutions for etching copper, which I would be happy to share. Ferric Chloride makes a tremendous mess, and will wreck stainless steel, so I would avoid it. ---
**Author:** ![Disheavel](https://avatars.discourse-cdn.com/v4/letter/d/e274bd/32.png) [@Disheavel](https://boards.straightdope.com/u/Disheavel)\ **Post date:** [May 13, 2017, 6:18pm UTC](https://boards.straightdope.com/t/working-with-ferric-chloride-hexahydrate/786535/4 "2017-05-13T18:18:54Z")
I am a chemist. Hydrated salts are the norm (on sigma-aldrich the anhydrous version is 10-100x as expensive)- you just scrape out the mass that you need. If the concentration and mass calculation assumed anhydrous, you just have to do the new calculation using a molecular mass of 270 g/mol (hexahydrate) vs. 162 g/mol (anhydrous). You can use an old butter knife to scrape or break the solid into the more manageable sizes. ---
**Author:** ![Patty\_O\_Furniture](https://avatars.discourse-cdn.com/v4/letter/p/96bed5/32.png) [@Patty\_O\_Furniture](https://boards.straightdope.com/u/Patty_O_Furniture)\ **Post date:** [May 14, 2017, 1:42am UTC](https://boards.straightdope.com/t/working-with-ferric-chloride-hexahydrate/786535/5 "2017-05-14T01:42:10Z")
> [@Disheavel](#): > > You can use an old butter knife to scrape or break the solid into the more manageable sizes. I wish I could. I tried using a bar spoon to dig into the substance and couldn’t break a single piece free. It’s like a block of cured cement in the bottom of the bottle. It seems the only way this stuff is coming out is if I break the bottle.