# Unable to recover Platinum from this..



## arsenic123 (Aug 10, 2015)

Hey guys I received a solution and salt today with Platinum aprrox 5 grams in a solution. The solution also contain Ammonium hydrogen bi carbonate and 5 gram of Platinum. The reason I know that there is a 5 gram of Platinum is that we started a 100 gram of Platinum sponge dissolved via aqua reiga and when I made the reaction using ammonia a 5 gram of black sponge was quickly settled in the first attempt. After second reaction using ammonia only 75 gram was dissolved and 25 gram was was left in solution with a sponge and I recovered 20 gram I couldn't recover the remaining 5 gram using aqua reiga. Please can some one help me recover the remaining platinum from the solution. 

Thank you.

Edited to make more sense.. I hope you guys can understand it. Thanks


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## Lou (Aug 10, 2015)

Please list out your steps taken in full and I'll troubleshoot


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## arsenic123 (Aug 10, 2015)

Hey Lou,

The steps are ..
1) 100 gram of PT sponge was dissolved in Ar and it dissolved completely.
2) We passed a reaction using ammonia and it dissolved 95 grams of PT and 5 gram of PT sponge was precipitated in black powder form.
3) We passed a second reaction and this time we extracted 75 grams Tetraammineplatinum(II) hydrogen phosphate in the form of white salt and that means 5 gram from step 1 and 20 gram from step 2 is still lying in the solution. I recovered 20 gram from that solution but I am unable to remove the remaining 5 grams. 

hope this helps..


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## Lou (Aug 10, 2015)

1. The sponge could not have been completely dissolved (did you filter the solution to be sure?)
2. Ammonia will not precipitate the Pt from the solution as anything other than ammonium hexachloroplatinate. If you were heating this with a hot plate, it is possible that the heat may have partially decomposed some of the yellow chloroplatinate back to metal, but this would only happen if the bottom of the vessel was quite hot. 
3. Your platinum is not in the form you think it is--unless you add a reductant, it is mixed Pt(II)/Pt(IV). Seems like you are making platinum Q salt for plating onto whatever--if so, you are missing a step or two (namely the reduction from Pt(IV) to Pt(II) to Pt(NH3)4Cl2, the chloride exchange to [Pt(NH3)4(OH)2] which is done prior to the reaction with phosphoric acid. 


4. Recovery: Adjust pH to 6.5 with formic acid and boil until the platinum is recovered. 

PM me and I'll help you figure this out further.

Lou


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