Oggas
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Filtering fine suspensions
I was going to try and find out the concentration of my hydrochloric acid by reacting a determined amount of it with an excess of sodium thiosulfate
to make sulfur that could be wheighed.
However, the sulfur that was made formed a fine suspension in the water and most of it seems to have passed through my filterpaper. This is a great
problem. So therefore after i searched around a little and found nothing useful i thought i could ask for help here.
So how does one go about to reduce a fine suspension to bigger chunks or clumps that can be filtered from the solution.
Thanks on forehand!
MvH
Oskar
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hkparker
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I have heard of filtering through activated carbon is effective at getting tini particles out, though it could be hard to mass after. Mass the dry
carbon before, filter, let dry completely, mass dry carbon + sulfur I suppose. Not clumping them together like you asked but I think that might work.
[Edited on 15-6-2011 by hkparker]
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"Nothing is too wonderful to be true if it be consistent with the laws of nature." -Michael Faraday
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bob800
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I would just let it sit for a day or two to form larger particles. I did this reaction once, and the next day all of the sulfur had formed larger
particles and coated the bottom of my container! Once this has happened, you could just decant off the water, rinse, and let your sulfur dry.
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MrHomeScientist
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In my experience just waiting a while seems to help, as bob800 said. If that doesn't work, try using larger quantities.
For example, I've done the chemical chameleon experiment, which reduces KMnO4 to MnO2. The MnO2 is an extremely fine solid suspension that colors the
solution yellow/orange. Usually, this settles out as the particles clump together after a few hours. One time, though, this didn't happen and the
color stayed around for days. To fix this I just repeated the demo by adding more KMnO4, which produced more suspended MnO2 and that allowed things to
start clumping up and settle out. In your case, maybe you could try using larger amounts of HCl and thiosulfate and see if that does anything for you.
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blogfast25
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Quote: Originally posted by Oggas  | I was going to try and find out the concentration of my hydrochloric acid by reacting a determined amount of it with an excess of sodium thiosulfate
to make sulfur that could be wheighed.
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Why bother with a troublesome gravimetrical method that’s extremely wasteful on a valuable chemical (thiosulphate) when you can determine it by acid
titrometry?
Even if you don’t have access to a burette, just carefully weighing the amount of sold sodium bicarbonate needed to approximately neutralise (end of
bubbles!) a known quantity of your acid can give you quite a reasonable estimate of acid strength.
For more accurate determinations, standardised acid-base titration of the acid with NaOH solution is inevitable.
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