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how to make up 85% ammonium sulphate solution - (Sep/29/2008 )

Hi guys,

I'm gonna make up 85% ammonium sulphate solution. My caculation is dissolve 850mg ammonium sulphate in H2O, make the total volume comes to 1 ml. By using this amount, I found it is impossible to make such a "huge" amount ammonium sulphate dissolve in only hundrdes of microliters water(of course total volue is 1 ml), whatever I do, including heating and vortexing. Later I put it in room temperature for 1 week, there are half of them undissolved.

Would anybody tell me whether my caculation is correct? or what should I do to get such solution?

Thanks a lot.


Can you make 10 ml instead of 1ml?

It is difficult to dissolve chemical in 1 ml

-Minnie Mouse-

The saturation point of water with ammonium sulphate is approx 540g/l or about 54% at 25 degrees C. You will not be able to dissolve ammonium sulphate to make 85%.


Perhaps you need 85% of saturation, not concentration?


Thanks guys, below is the inforamtion about the ammonium sulphate solubility in water from wikipedia:

70.6 g/100 mL (0 °C) and
103.8 g/100 mL (100 °C)

and the protocol says I need use 85% ammonium sulphate to dissovle some reagents. So I think it is supposed 85g can be dissolved in some quantity of water(which makes the total volume to 100ml).

But anyway, I found I could not make it out.


it could be 85% saturation rather than 85% w/v.

Some protocol use percentage saturation rather than w/v


whenever using ammonium sulfate (at least in my experience) percentage refers to percent of saturating.