concentrated h2so4

[arthur kierski]

what is considered concentrated h2so4?98%(full stenght),60%,50% ?
i am asking this question because i want to dissolve rh from a pt-rh mixture of black pgm powder cemented out with zn,with h2so4----leaving the pt powder behind in the botton of the beaquer-----
the powder is a mix of 90%pt,10%rh---- i will boil this solution for 4hours-----
thanks for information
Arthur

 

[samuel-a]

Yes 98% is what you would want to use to dissolve Rh.

Is the powder consist of two different metals or is it an alloy of the two ?
Dissolving the Rh from an Pt/Rh 90/10 alloy will not be possible with sulfuric acid.

 

[arthur kierski]

Sam,it is 2powders and not an alloy

 

[lazersteve]

Arthur,

The boiling 98% sulfuric acid (be very careful!) will work on dissolving some of the Rh from the mixed powders, but it will take several extractions to dissolve all of it.

Remember you cannot filter concentrated H2SO4 with normal filters so allow the solution to cool and settle then siphon off the sulfate soluiton and repeat until you not longer get a red brown solution from the extraction.

After the last extraction wash the remaining powder with several rinses of water to get the last of the sulfate out of the Pt powder.

Steve