HCl Bright Yellow

[Miami Reef]

I store my HCl (hydrochloric acid) in a pickle jar.

I see bright yellow condensation. It was stored in this jar for months without yellowing, so I’m not sure why it is now producing this bright, yellow fluid.

What is it?

 

[Randy Holmes-Farley Verified Community Expert]

I suspect it may be traces of dissolved iron, perhaps oxidizing to the ferric form that is more highly colored than the ferrous form.

https://www.nedt.org/muriatic-acid-what-it-is-and-why-its-a-cleaning-product/
"Usually, muriatic acid includes iron impurities, giving it a yellow color instead of HCI’s colorlessness."

 

[Miami Reef]

I suspect it may be traces of dissolved iron, perhaps oxidizing to the ferric form that is more highly colored than the ferrous form.

https://www.nedt.org/muriatic-acid-what-it-is-and-why-its-a-cleaning-product/
"Usually, muriatic acid includes iron impurities, giving it a yellow color instead of HCI’s colorlessness."

Thank you.

Just out of curiosity, which form of iron is more available to seawater organisms? Does iron frequently alternate forms in tanks?

 

[Randy Holmes-Farley Verified Community Expert]

Thank you.

Just out of curiosity, which form of iron is more available to seawater organisms? Does iron frequently alternate forms in tanks?

That's a good question without a perfect answer. There are many complexities and studies of it, including solubility differences, different binding by siderophores, different binding by uptake proteins, etc.

I had a full answer to this in some thread, but cann't fined it. Here's from an older response:

This paper discusses how ferrous iron that gets oxidized can become less bioavailable

ftp://ftp.soest.hawaii.edu/glazer/Chen%20References/Papers1/Pham%202008%20Oxygenation%20of%20Fe%20II.pdf