From: Poutnik4NNTP@gmail.com   
      
   On 08/27/2015 02:53 AM, c2o.pro.br@gmail.com wrote:   
   > Em quarta-feira, 26 de agosto de 2015 16:06:02 UTC-3, Poutnik  escreveu:   
   >>>   
   >>> What about to produce standard solutions   
   >>> by controlled dilution of Natrium hypochlorite - bleaching agent ?   
   >>>   
   >>> Than doing some simple comparative colorimetry   
   >>> by dropping agents into tested water, min and max standard solution ?   
   >>>   
   >> With variant the tested water would be compared   
   >> just toward coloured foils/glass/sealed tube,   
   >> representing colour of min/max chlorine concentration.   
   >   
   > That is the question.   
   >   
   > Where I'll find a sodium hypochlorite solution with known concentration?   
   >   
   > Sodium hypochlorite is usually sold to the end consumer in the form of   
   Bleach with active chlorine content in the range of 1.75 and 2.75% of active   
   chlorine.   
   > But this solution is very unstable.   
      
   You are probably right. You was thinking about just rough precission,   
   but it is probably bad even for that.   
   >   
   > I have tested a kit for colorimetric analysis used to monitor the chlorine   
   concentration in swimming pools. But I found very difficult to identify the   
   concentration from the color card scale and found that uncertainty is very   
   large.   
      
   OTOH, colorimetric kit is in large use by water treatment companies   
   to monitor chlorine levels at determine dpoint of water pipe system.   
   I used it a lot in past, working in their lab, and I did not notice   
   troubles. Required range was  0.05-0.3 mg Cl2 / L.   
      
   > I plan to measure the current during a time interval in a electrolysis of   
   NaCl solution and use the Faraday's law to calculate the amount of Cl2   
   produced.   
   > What do you think about?   
      
   For low target concentrations, there would loses by secondary reactions   
   across the system, and on anode as well, e.g. impurities of material.   
      
   I would definitely recommend statistical evaluation   
   or supposed ( generated ) versus measured chlorine level.   
      
   I would suggest rather to produce higher chlorine levels,   
   and than to dilute it,   
   then to produce target low concentration directly.   
      
      
      
   --   
   Poutnik ( the Czech word for a wanderer )   
      
   Knowledge makes a great man humble, but a small man arrogant.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)