[randomclem]

Hey there,

I'm trying to find a ferrous or ferric solution that would be clear when dissolved into a liquid.
I know that Acetate is usually brown/orange, chloride is yellow(?), sulfate is green, etc.
I'm looking for something that is colorless.

Any thoughts?
I appreciate your time and *delete me*

[Borek]

when dissolved into a liquid.

What liquid?

And what is your target concentration?

[randomclem]

Hey Borek,

Thank you for taking the time to reply to my post!

The liquid isn't super important - just looking for something that is safe to handle without some hardcore hazmat gear.   
As for the concentration - the more iron the better.

Long story short, I made a ferrous acetate solution that was perfect - in terms of what I was trying to get it to do (react with tannins).
The solution was clear when made, and clear when I bottled it into a sealed plastic bottle.
After a few hours, I noticed the solution starting to turn orange/brown in color - I bottled the same solution into multiple bottles, and noticed that each one has a slightly lighter or darker orange/brown tone to it.

So, the color issues is something I am trying to avoid..  Also the smell of acetic acid would be awesome to avoid if possible.
I'm simply looking for a liquid that is odorless/colorless and has a high concentration of iron.

Any thoughts?
I appreciate the input!

[Corribus]

Your problem is that iron in either of its common oxidation state is open shell and therefore has d-d electronic transitions that occur usually in the visible range.  These transitions are weak because they are almost always both Laporte- and spin-forbidden, and so the coloring is usually light - but it'll still be visible in practically any aqueous solution of sufficient concentration.  Dissolution of most ferrous or ferric iron salts result in the formation of the aquo complex:

http://en.wikipedia.org/wiki/Metal_aquo_complex

Therefore, the color is going to be pretty hard to get away from unless you can find one where the d-d transitions extend into either the UV or NIR region.  I don't know off the top of my head any iron salts that do this, particularly in water.  Your best bet may be some kind of iron complex in an organic solvent, but these are often quite intensely colored - e.g., bis(terpyridyl)iron is an intense purple color in acetonitrile due to a fairly strong MLCT transition, think concord grape juice.  Sometimes this color vanishes in metal-ligand complexes if you can form a radical cation using a sufficiently powerful oxidant (or electrochemical setup), but you'd have to do some research to find out if there is a convenient option available for an iron containing species.

What by the way is "high concentration of iron" to you?  Some might consider ppm high concentration.  Others may not.  This will be an important consideration.

[randomclem]

Hey Corribus,

Thank you for replying to my post - the information you've supplied was very helpful!

As I am a novice at chemistry - may I ask, what would be the best way for me to measure the content of iron in my existing solution?
I really am not sure how to go about doing that - any information would be greatly appreciated!

[Corribus]

As I am a novice at chemistry - may I ask, what would be the best way for me to measure the content of iron in my existing solution?
I really am not sure how to go about doing that - any information would be greatly appreciated!

The best (most quantitative) way is probably ICP(-MS/-AES) or GF-/F-AAS, which are used routinely for trace metal analysis in analytical laboratories. 

http://en.wikipedia.org/wiki/ICP-MS
http://en.wikipedia.org/wiki/ICP-AES
http://en.wikipedia.org/wiki/Atomic_absorption_spectroscopy

However these are sophisticated and expensive instruments that you may not have access to.  Since there is a general consumer interest for testing water for iron content (hard water evaluation), I believe there are iron test kits available.  I do not know much about them, how quantitative they are, or how easier they are to use.  I presume they are colorimetric in nature (quantify iron content by color change).  If you do a google search for "iron test kit", you'll find some options.