RU_KLO - 22-5-2023 at 06:17
hi,
Im trying to find metal oxalates solubility, if possible a full chart (every metal oxalate)
The main idea is to device an analitycal qualitative scheme.
1) If a substance is (highly) hygroscopic, this means that is solubility is high? (or solubility and hygroscopicity are not 100% related, ie, there
are hygroscopic substances that are not/slightly soluble?)
(for example found that cobalt oxalate is highly hygroscopic, but its solubility is not stated.)
2) Do oxalates behave like carbonates, in the way carbonates reacts with mineral acids to produces its salts + CO2?
3) Do metal oxalates + NaOH/KOH -> metal hydroxides?
4) Does strong heating decomposes metal oxalates to give metal or will I get an oxide? (o anything else)
Thanks
clearly_not_atara - 22-5-2023 at 08:07
Practically all metal oxalates have low to very low solubility, except potassium, rubidium, and caesium. It's hard to do any kind of double
displacement for this reason, although it might be possible to do 2 NaF + K2C2O4 >> 2 KF + Na2C2O4.
DraconicAcid - 22-5-2023 at 08:55
If you want to know how soluble a metal oxalate is, you can probably find Ksp values for most of them. However, many transition metals will form
complexes with oxalate. Add a bit of oxalate to the solution, and the metal oxalate precipitates; add more and it redissolves.
Metal oxalates will react with acids to give oxalic acid and a different metal salt.
Some metal oxalates will react with hydroxide to give oxalate ions and metal hydroxides. Compare the Ksp values of the hydroxide and the oxalate.
Copper will; calcium won't.
Strong heating of MC2O4 will generally give MO, CO, and CO2. Only a metal which is very easily reduced (such as silver) will give the metal.
clearly_not_atara - 22-5-2023 at 13:00
You don't have to go all the way to silver. Cobalt nanoparticles can be formed from the oxalate:
https://pubs.rsc.org/en/content/articlelanding/2017/cc/c7cc0...
I would infer that other metals less reactive than cobalt, including nickel, copper, molybdenum, tungsten and tin, could also form nanoparticles from
the oxalates. But these are typically pyrophoric.
[Edited on 22-5-2023 by clearly_not_atara]
DraconicAcid - 22-5-2023 at 14:12
True. I was thinking that iron gave the oxide, but now I remember it's a pyrophoric mixture of iron powder and iron(II) oxide powder.