Sciencemadness Discussion Board - Turn Mcrs Chloride to Mcrc Salts?

Turn Mcrs Chloride to Mcrc Salts?

ScienceHideout - 24-10-2011 at 12:33

I am a bit curious- I want to use my mercurous chloride in a reaction- but- it doesn't dissolve (as you already know).

To make this "poisonous garbage" useable, is there anything that I can do to make it a nice mercuric salt. I tried to see if I could react it with a mineral acid- I tried HCl and H2SO4, and after failing, I thought I'd ask you.

And I don't want to decompose it with light.

Before you post- I don't need the usual "Mercuric Salts are too dangerous for a home chemist" because I don't plan on eating it- I plan on keeping it in a locked cabinet until it should be used for an experiment I will conduct IN MY HOOD with a face shield, goggles, and gloves.

turd - 24-10-2011 at 12:49

Oxidation with H2O2, KMnO4, K2CrO4, K2Cr2O7 or aqua regia? Also I think it should react with hot conc. H2SO4 to give HgSO4, which can be dissolved in acidic solution. Conc. HNO3 should work as well. Or disproportionate with NH4OH (there is no Hg2O!) and dissolve in hot conc. H2SO4.

Neil - 24-10-2011 at 12:52

Playing with Hg and you haven't even looked at the wiki page for the compound you are using?

ScienceHideout - 24-10-2011 at 14:39

My teachers always say

"Wikipedia can't always be reliable"

I could edit the wiki page for Lead Acetate and put it as a non-poisonous substitute for sugar- and say it has no effective dose!

Bot0nist - 24-10-2011 at 14:55

Sigh... If you use wiki right, and find supporting sources, you have nothing to fear from stupid spoofs like that.

Neil - 24-10-2011 at 15:00

No, you are right; Wiki is not to be taken without a salt shaker or two but as a start point it normally provides a link to a MSDS for whatever chemical it has an entry for and in your case it provides the data which was essentially summarized by Turd.

The data could have been followed up on and verified all of which would be a very good idea if you are to work with a substance so lingeringly toxic as mercury. I assume your teachers also point out that reading something on a forum doesn't make it any more reliable?

Edit: Bot0nist got there first...

[Edited on 24-10-2011 by Neil]

ScienceHideout - 24-10-2011 at 15:17

I would much rather trust everyone here better than the spoofs of Wikipedia. I remember once I was doing research, and someone added an extra word to Avogadro's name. I forgot what it was... DeCamillo or something like that...

Anyways, I also feel that lots of people exxagerate the toxicity of Hg... they make it sound like it is worse than benzene- this contact poison reputation. In fact, I could bet all of our grandparents used to PLAY with it for the fun of it! They were all fine!

Neil - 24-10-2011 at 15:38

...metallic mercury and the salts of mercury are a little different

Ie metallic mercury embolism - The Wiz posted this somewhere;
http://circ.ahajournals.org/content/91/12/3020.full

Vs the salts

Mercuric chloride
Toxicological Data on Ingredients: Mercuric chloride: ORAL (LD50): Acute: 1 mg/kg [Rat.]. 6 mg/kg [Mouse]. DERMAL
(LD50): Acute: 41 mg/kg [Rat].

http://www.sciencelab.com/msds.php?msdsId=9924616

Mercuric nitrate monohydrate
Toxicological Data on Ingredients: Mercuric nitrate monohydrate: ORAL (LD50): Acute: 26 mg/kg [Rat]. DERMAL (LD50):
Acute: 75 mg/kg [Rat].

http://www.sciencelab.com/msds.php?msdsId=9924618

methylmercuric chloride

Toxicology

Very toxic by inhalation, ingestion and through skin contact. Danger of cumulative effects. Note low LD50s.

Toxicity data
(The meaning of any abbreviations which appear in this section is given here.)
ORL-GPG LD50 21 mg kg-1
IPR-RAT LD50 11 mg kg-1
IPR-GPG LD50 7 mg kg-1
IPR-MUS LD50 17 mg kg-1
ORL-MUS TD50 1.91 mg/kg/day.

http://msds.chem.ox.ac.uk/ME/methylmercury_chloride.html

I'd much rather trust most of the people here then wiki sans verification but I would still never mix X with Y until I had independently verified whatever was said.

hkparker - 24-10-2011 at 16:05

Mercury as an element likes to stick to itself a lot, and therefore doesn't penetrate skin well, so short contact will almost never cause long term damage. Now what you are trying to make is a soluble mercury salt, which is much much more toxic. A soluble mercury salt could be much more easily absorbed through skin.

<a target="tab" href="http://en.wikipedia.org/wiki/Karen_Wetterhahn">An extreme example of how mercury can be extremely toxic</a>.

The salts you are trying to make will not be that toxic of course but that give you an idea of how the toxicity of an element does not speak for its compounds. You can look up the values for toxicity on an MSDS sheet. Look for a value called "LD50". This is the amount (in mg/Kg of body weight most of the time) that would be needed to kill 50% of a population. For example, NaCl has an LD50 of just about 3000mg/Kg.

Benzene = 930mg/Kg[oral/rat].
Phenol = 317mg/Kg[oral/rat].
Mercuric Nitrate = 26mg/Kg[oral/rat].
Mercuric Chloride = 1mg/Kg[oral/rat].

Pretty big difference between benzene and mercuric salts.

There are similar measurements such as LC50 for gasses (lethal concentration for 50% population kill) and those usually have a time in their units as well.

Also, if you pay attention to what has a source on wikipedia, it can be extremely useful. The idea that wikipedia is useless is very misinformed.

http://avogadro.chem.iastate.edu/MSDS/phenol.htm
http://www.sciencelab.com/msds.php?msdsId=9927339
http://www.sciencelab.com/msds.php?msdsId=9924618
http://www.sciencelab.com/msds.php?msdsId=9924616

EDIT: Neil beat me to it

[Edited on 25-10-2011 by hkparker]

woelen - 25-10-2011 at 01:32

HgCl can be converted to a solution of HgCl4(2-) ions by adding concentrated HCl to it and then adding 30% H2O2. All of the HgCl will dissolve slowly. Don't add the H2O2 at once, but add this in small amounts, otherwise you'll end up with a lot of foam and a plume of oxygen/chlorine mix. If the dissolving of the HgCl is slow, then heat the liquid, such that it just does not boil.

The concentrated acid and H2O2 can be boiled off, but this MUST be done in a fume hood or outside. The fumes of HCl and Cl2 are bad enough already, but almost certainly some HgCl2 will volatilize as well, so know what you are doing. I personally do not recommend the boiling down of this liquid until solid HgCl2 appears. There is too much risk of poisoning yourself.

Another much safer option is to keep the mercury(II) in solution and use that solution for experiments. In order to achieve this you need to heat for a while and boil for a few minutes. This destroys all remains of H2O2 and makes the liquid just acidic. You can add a 10% solution of NaOH to neutralize the acid and the solution then can be used as is for experiments with aqueous HgCl2. The additional NaCl hardly interferes with most experiments.

turd - 25-10-2011 at 07:50

Quote: Originally posted by woelen

HgCl

I've never seen it written like that. Hg+ is practically always written as Hg22+. On the other hand nobody ever writes P4O10.

If the original poster failed to dissolve Hg2Cl2, I can only assume that he didn't really try.

woelen - 25-10-2011 at 09:11

You are right about HgCl, it is much better to write Hg2Cl2. The ion Hg(+) does not exist, it is Hg2(2+).

mr.crow - 26-10-2011 at 08:42

I like the H2O2 oxidation idea, seems much better than adding nitric acid

If you want something to do with your HgCl2 try adding excess KI solution to precipitate the very pretty and insoluble HgI2

Clean up any mercury waste with sodium polysulfide solution. Of course you should have good lab skills to do this

woelen - 26-10-2011 at 09:10

The use of KI is an option, but assure that not too much iodide is added. If you add too much iodide, then the brilliant scarlet precipitate redissolves again and a complex ion is formed.

mr.crow - 26-10-2011 at 09:19

Good point, forgot about that

A slight excess of iodide ions will further reduce the solubility (common ion effect)

woelen - 26-10-2011 at 22:52

There is another very funny thing about the scarlet-red HgI2. When it is formed initially, then it is yellow and it turns scarlet-red in one or two seconds or so. The change of color also is very nice to see.

http://woelen.homescience.net/science/chem/exps/hgi2/index.h...

On careful heating the compound also turns yellow and when it cools down then it remains yellow, until it is agitated mechanically, e.g. by strong shaking or crunching. With silver(I) and copper(I) ions also very interesting compounds can be made.

http://woelen.homescience.net/science/chem/exps/hgi2_thermoc...

turd - 27-10-2011 at 01:36

Quote:

In the first experiment, there first is a gradual change of color (which also is not really striking) and at a certain temperature, there is a sharp transition from one color to another. On cooling down, the color does not simply revert. It really seems as if a new compound is formed.
In the other two experiments, there is a gradual change of color with temperature. When temperature increases, then a certain color change occurs and when temperature decreases again, then changes occur in reverse order. For each temperature, there is a color, and the color does not depend on the history of heating.

This is not very surprising. First order phase transition: Sudden change, hysteresis. Second order phase transition: smooth change of order parameter, no (or little) hysteresis. I've seen first order phase transitions where you could get the low temperature phase only by prolonged heating slightly below the phase transition temperature.