Sciencemadness Discussion Board

Salts with two different ions?

Jackson - 26-9-2018 at 09:19

When you react NaHSO4 with NaCl you get an equilibrium that looks like:
NaHSO4 + NaCl <—> HCl + Na2SO4

My question is, if you were to replace the NaCl with KCl would the reaction work like this:

NaHSO4 + KCl <—> HCl + NaKSO4

If the HCl was boiled off could the NaKSO4 be collected?

12thealchemist - 26-9-2018 at 09:54

I'm not sure if discrete NaKSO4 crystals could be collected, or whether one would end up with a mixture of Na2SO4 and K2SO4. It's something I've wondered from time to time, but have never tried the actual experiment.

On the subject of confirming the product as one or the other, I imagine you would have to distinguish based on crystal system or some other similar method. Gravimetry on water of crystallisation? Sodium sulphate has hydrates, potassium sulphate does not. I'm not sure about sodium potassium sulphate.

MrHomeScientist - 26-9-2018 at 09:55

I don't think so. Potassium ions are much larger than sodium ions, so I wouldn't think they could replace each other that easily. I'd expect a mixture of Na2SO4 and K2SO4 crystals.

unionised - 26-9-2018 at 10:58

I don't know about sulphate but...
https://en.wikipedia.org/wiki/Potassium_sodium_tartrate

And the other way round
https://www.chemicalbook.com/ProdSupplierGWCB32274321_EN.htm