Australia's Science Forum

I have "pickle", an acid powder from the metalwork room. How do I identify it? I would think it was HCl but curiosity has me wanting to prove it.

Pickling is a metal surface treatment used to remove impurities, such as stains, inorganic contaminants, rust or scale from ferrous metals, copper, precious metals and aluminum alloys. A solution called pickle liquor, which usually contains acid, is used to remove the surface impurities. Wikipedia

I know that some Pickle used for stainless steel contains Hydroflouric Acid which is a DET banned chemical .....but its a liquid .

You gave a powder that is added to water to make a pickle solution .

A quick google showed Citric acid and sodium bisulpfate being common .One is food grade , the other is toxic .

Bottom line though to me is if its not labelled , then you have no access to an SDS and it should not be stored or used .

mtg wrote: ↑23 Jul 2019, 11:34 How do I identify it? I would think it was HCl but curiosity has me wanting to prove it.

You could drop some silver nitrate into a sample . The Chlorine will cause a white precipitate .

YAY, The "Pickle" is HCl. (AgNO3 test) We used to make up a % to dip metal before enamelling as I recall. Probably same as the powder you get to chlorinate pools. It amazes me how the Art and Metal/Wood work have these sort of labels.