Sciencemadness Discussion Board
Not logged in [Login ]
Go To Bottom

Printable Version  
Author: Subject: What are the best salts to keep?
Vhin
Harmless
*




Posts: 5
Registered: 21-5-2012
Member Is Offline

Mood: No Mood

[*] posted on 24-5-2012 at 20:53
What are the best salts to keep?


I know that a lot of salts tend to be pretty "malleable", in that they can easily be changed into a different (but related) salt. So, keeping in mind the widest variety of cations and anions, ease of turning them into other salts, and ease of storage, what are the "best" salts to keep on hand?

If I'm unclear, I mean in terms of the fact that it's silly to have like five Copper salts, or five Sulfates, instead of just one and making what you need.
View user's profile View All Posts By User
AndersHoveland
Hazard to Other Members, due to repeated speculation and posting of untested highly dangerous procedures!
*****




Posts: 1986
Registered: 2-3-2011
Member Is Offline

Mood: No Mood

[*] posted on 24-5-2012 at 20:56


No, actually it can be useful to keep all different types of chemicals for available access, even if you think you are never going to use them. There are always new things to learn, and (very frequently) unexpected uses for old chemicals.
View user's profile Visit user's homepage View All Posts By User
Vhin
Harmless
*




Posts: 5
Registered: 21-5-2012
Member Is Offline

Mood: No Mood

[*] posted on 24-5-2012 at 21:00


While, yes, it would be best to buy reagent grade versions of all the salts, this isn't really possible due to the cost.

If they're fairly easy to make, I'd rather make them for my purposes then spend the money to buy them.
View user's profile View All Posts By User
DJF90
International Hazard
*****




Posts: 2266
Registered: 15-12-2007
Location: At the bench
Member Is Offline

Mood: No Mood

[*] posted on 24-5-2012 at 21:13


I guess its quite dependent on the metal salts you wish to deal with. For example, making salts of the first row transitions metals would be considered fairly facile (assuming no need for anhydrous) as they all form insoluble oxides or carbonates which can be precipitated, thoroughly washed, and dissolved in the acid which corresponds to the anion you want. If you dont have the requisite acid, things get a bit trickier in that you generally have to resort to a metathesis reaction.

These work best when both starting materials are readily soluble, and one of the products is insoluble. Precipitation of the transition metal oxides/carbonates is an example of this. Another example is in the formation of alkali metal salts containing an anion which is readily procured as the barium salt. Metathesis with the alkali metal sulfate precipitates barium sulfate, leaving the desired compound in solution. Careful not to over-add the sulfate solution otherwise you'll contaminate your product. An example which springs to mind is hypophosphite. Ba(OH)2.8H2O is treated with (white?) phosphorus to afford phosphine gas (waste) and barium hypophosphite. Metathesis with either dil. H2SO4 or metal sulfate solution yields barium sulfate (ppt) and either H3PO2 or Mx(H2PO2)y in solution.
View user's profile View All Posts By User
woelen
Super Administrator
*********




Posts: 8011
Registered: 20-8-2005
Location: Netherlands
Member Is Offline

Mood: interested

[*] posted on 24-5-2012 at 22:39


Indeed, selecting a well-chosen set of chemicals is the best thing you can do. If for instance you want to experiment with copper salts, then you should take one or maybe two copper salts with a non-reactive anion. I would like copper sulfate or coper nitrate for such experiments. E.g. copper dichromate would be a bad choice, because the anion in that latter case has very specific properties which certainly would interfere mostly with the properties of the copper salt.

I have written a webpage about what chemicals to buy and where to start. It may be helpful for you. Keep in mind that the webpage is written with inorganic home chemistry in mind. If you want to do a lot of organics, then you need to find other info.

http://woelen.homescience.net/science/chem/misc/chemicals.ht...




The art of wondering makes life worth living...
Want to wonder? Look at https://woelen.homescience.net
View user's profile Visit user's homepage View All Posts By User
AndersHoveland
Hazard to Other Members, due to repeated speculation and posting of untested highly dangerous procedures!
*****




Posts: 1986
Registered: 2-3-2011
Member Is Offline

Mood: No Mood

[*] posted on 24-5-2012 at 22:51


Quote: Originally posted by Vhin  
it would be best to buy reagent grade versions of all the salts, this isn't really possible due to the cost.

Usually the carbonates or hydroxides are best. You can always mix with acids to obtain the respective salts.
For example, copper sulfate by reacting coppric oxide with sulfuric acid.

In some cases (not with the transition metals) certain salts can be prepared by boiling the hydroxide or (carbonate) with the respective ammonium salt. For example, calcium nitrate from calcium carbonate and ammonium nitrate.

This thread should be moved to 'beginnings'...

[Edited on 25-5-2012 by AndersHoveland]
View user's profile Visit user's homepage View All Posts By User
Bot0nist
International Hazard
*****




Posts: 1559
Registered: 15-2-2011
Location: Right behind you.
Member Is Offline

Mood: Streching my cotyledons.

[*] posted on 24-5-2012 at 22:54


I find calcium chloride handy often, as it is an easily available and cheap source of water soluble calcium. This question is a bit subjective.What kind of chemistry do you plan on focusing on? Many here love to have a nitrate and nitrite salt handy, as they are very useful in a lot of amateur energetic research.

IMO, The usefulness of the salt is in the eye of the beholder(chemist).

[Edited on 25-5-2012 by Bot0nist]




U.T.F.S.E. and learn the joys of autodidacticism!


Don't judge each day only by the harvest you reap, but also by the seeds you sow.
View user's profile View All Posts By User
Rosco Bodine
Banned





Posts: 6370
Registered: 29-9-2004
Member Is Offline

Mood: analytical

[*] posted on 24-5-2012 at 23:01


nitrates, carbonates, hydroxides, sulfates, chlorides in that order generally are the economical salts which you can manipulate changeably from one of those salts into another one of those salts by some relatively easy and economical method. Often it is the relative consumer demand mass production market for a particular salt which will make that particular salt the most economical form supplied commercially as a standard item while another less in demand salt will be many times more expensive as a special order item.
View user's profile View All Posts By User
longtermmadscientist
Harmless
*




Posts: 9
Registered: 12-12-2010
Member Is Offline

Mood: No Mood

[*] posted on 26-5-2012 at 12:10


If you’re intending on using those compounds for general- purpose experiments later on, you’ll be looking for a salt which is stable against both hygroscopy and efflorescence. For example, if you choose chlorides as a storage medium for many metals, then you may find that your “dry” compound will gain weight over time, even when stored in “airtight” containers, meaning you may have to go to the trouble of drying your compound by heating (assuming that you don't have a dessicator) before you use it. This wouldn’t be a problem for alkali- and alkaline earth- metals, but may be tricky with the chlorides of the f and d block elements (the former especially), which may partly hydrolyse in the process. And if you choose a compound which is known to lose some water of crystallisation at ambient temperature and humidity, then cobalt chloride and copper sulphate hydrates are not good choices, either. All this isn’t likely to be a problem, or hardly at all, if you have air-tight containers, but it has been an issue for me, which is why I mention it.

Also, obviously, if you want to do wet chemistry experiments with these chemicals at some point, you will want a water soluble compound, like others have mentioned here. Having a compound with no strongly oxidising or reducing properties in particular may be wise, especially if you’re not sure what experiments you’re likely to be doing.
Overall, I’d say sulphates are a good all- round choice, but you need to do research on the individual sulphate you’re thinking of storing.

If, however, you’re thinking of not using the salts for future experiments, but rather as an example of a particular element in a particular oxidation state, then I’d opt for orthophosphates, as these are on the whole insoluble or comparatively insoluble, and rather chemically stable.

It all depends on what you want to use the salts for, and it’s always best, I find, to do individual research on the individual compound you’re contemplating.
View user's profile View All Posts By User

  Go To Top