Picric acid is stored under a layer of water to prevent an explosion.
What is the right way to measure the amount of picric acid that taken out? It is wet and containing water.
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$\begingroup$ Only about 1–2% of picric acid would be actually dissolved in water at room temperature, so without consulting any literature sources I guess it would be enough to just distribute the dispersed substance on a surface and let it dry for a while. $\endgroup$– andselisk ♦Sep 29, 2019 at 18:47
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2$\begingroup$ To let it dry is simple, but SDS says not to dry as it is very unstable and may cause explosion ... $\endgroup$– VGraninSep 29, 2019 at 18:56
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1$\begingroup$ Well, you have to take certain precautions (maintain purity, avoid rapid heating/sparks/shocks etc.) and don't accumulate substantial amounts over months. $\endgroup$– andselisk ♦Sep 29, 2019 at 19:05
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1$\begingroup$ You may have to dry it in an inert and safe place and then re-wet it/make a known solution in a controlled manner so you can weigh it safely. I worked with another shock/friction sensitive explosive and that's how the lab techs and researchers worked with it. You have to have very good safeguards and lab practices for the drying portion. You may want to consult with your lab/university safety person, they may be able to find more resources on how to best handle the material. $\endgroup$– J. AriSep 30, 2019 at 12:29
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2 Answers
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If accuracy is not essential, weigh a small amount drained for a fixed time but still wet, and then weigh again dried, to find the ratio of wet-to-dry weight (carefully disposing the dried, sensitized, explosive without destroying the scale or personnel).
Though this could give a rough idea of the actual dried weight, it would vary from batch to batch and with temperature.
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Find some nice instruction:
http://nzetc.victoria.ac.nz/tm/scholarly/tei-Bio06Tuat03-t1-body-d2.html
As Picric Acid stored under layer of water, we could know it's concentration in the water. It should be enough for most of the applications.
Temperature ° C. grams picric acid/100 grams solution
- 0 | 0.67
- 10 | 0.80
- 20 | 1.10
- 30 | 1.38