# ammonium hexachloroplatinate with little reagents



## sony (Sep 14, 2012)

Hello there,

In a quest to isolate some ammonium hexachloroplatinate without having to boil down solutions i wonder if it would be possible to do the following:

Dissolve 10 grams (0.0513 mol) of Pt in 61 grams of 37% HCl ( about 0,3078 mol, 12 molar equivalents vs Pt) and 19.11 gram 68% HNO3 (0.205 mol, 4 molar equivalents vs Pt) if everything dissolves with heating there would only be a minor amount of NOx gasses and probably barely any HNO3. From there if i would add enough ammonia to neutralize the excess HCl would the ammonium hexachlorplatinate freely precipitate? (perhaps add extra NH4Cl to get to correct saturation levels). 

Basically my biggest question is if a small amount of NOx gas and perhaps a tiny amount of HNO3 would interfere with the precipitation if only pure Pt is used?


----------



## Lou (Sep 14, 2012)

You can precipitate it from aqua regia but it will start to redissolve because ammonium can be oxidized. You can use KCl instead, chill and add alcohol. Make sure there isn't much nitric acid left.


----------



## lazersteve (Sep 14, 2012)

Pt will only precipitate if the solution is concentrated enough for the ammonium salt to precipitate. If the solution is too diluted the salt will not precipitate.

Steve


----------



## sony (Sep 15, 2012)

Thanks for the replies.

Wikipedia states that the solubility of ammonium hexachloroplatinate in the presence of 1M NH4Cl is 0.0028 g /100 mL but from what you would say is that if there is 1 gram of ammonium hexachloroplatinate present in 100 mL and to this solution is added 0,1 mol NH4Cl there will be no precipitate at all?

I also wonder if it is recommended to saturate the solution with ammonium chloride instead of adjusting to a 1M solution to decrease the solubility of the ammonium hexachloroplatinate or would this be counterproductive?


----------



## sony (Sep 23, 2012)

I managed to dissolve all the Pt but i had to use little over double the amount of nitric acid that i had calculated.

The precipitation went fine but i decided to boil down the solution which was not that troublesome as i had expected dissolved the hexachloroplatinate from 5 gr Pt in 50 ml H2O and adjusted to a 100 ml 2M NH4Cl solution i believe i have recovered most of the ammonium hexachloroplatinate.


----------

