[ajcamber]

I wasn't sure if this was the correct board to post to but here it goes.  I am trying to prepare a sodium polysulfide solution per the ASTM B298.  I says to make a sodium polysulfide solution (sp gr 1.142) --make a concentrated solution by dissolving sodium sulfide crystals in distilled water until the solution is saturated at about 21°C, and adding sufficient flowers of sulfur (in excess of 250g/L of solution) to provide complete saturation, as shown by the present in the solution of an excess of sulfur after the solution has been allowed to stand for at least 24h.  Make the test solution by diluting a portion of the concentrated solution with distilled water to a specific gravity of 1.135-1.145 at 15.6°C.  I have a hydrometer set.
I have never mixed solutions via specific gravity before and I am really confused about this whole process, please help.

[marquis]

I am not familiar with astm B298.

And you give a few details? Are you using this solution to find the spec gravity of a solid?

Thanks

[curiouscat]

Can you post the ASTM B298 standard?

[Arkcon]

Can you post the ASTM B298 standard?

Probably not, it is something you have to buy.  However, when I Google for it, I get a link like this:  http://www.astm.org/Standards/B298.htm  And the abstract we get for free seems to have nothing to do with sodium polysulfide.  I don't even see how poly sulfide is applicable to The Standard Specification for Silver-Coated Soft or Annealed Copper Wire.

I didn't even know it was possible to dissolve sulfur in NaOH.  I'd have thought someone would have mentioned it before when people ask what sulfur is soluble in, even though this isn't actually a solution.  Is it really that simple to make?  Seems to me like it sould only exist at high temperatures and under pressure.

As to the real question, how you make solutions according to specific gravity, I suppose you'd just use repeated trial and error to get it in the range you want?  But does that work -- you make a solution of sodium polysulfide and it can be diluted to any level.?  Will it not decompose and drop the sulfur out at some point?

[ajcamber]

Sodium Polysulfide is used to verify the contunity of silver coating on silver coated copper wires.  If the silver coating is not continuous then the sample turns black, because this solution turns the copper black.
The segment from the ASTM:

8.4.2.1 Sodium Polysulfide Solution (sp gr 1.142)—Make a
concentrated solution by dissolving sodium sulfide crystals
(cp) in distilled water until the solution is saturated at about
21°C, and adding sufficient flowers of sulfur (in excess of 250
g/L of solution) to provide complete saturation, as shown by
the presence in the solution of an excess of sulfur after the
solution has been allowed to stand for at least 24 h. Make the
test solution by diluting a portion of the concentrated solution
with distilled water to a specific gravity of 1.135 to 1.145 at
15.6°C. The sodium polysulfide test solution should have
sufficient strength to blacken thoroughly a piece of clean
uncoated copper wire in 5 s. The test solution used for testing
samples shall be considered exhausted if it fails to blacken a
piece of clean copper as described above.