# Last edited on 2017-02-07 06:23:35 by jstolfi

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2016-12-25

Testing the "CaO" from Asher

  I had bought three 1 kg packets of "CaO" (cal virgem, burned lime) from Asher
  in separate occasions.  The packets were thick sealed PE bags.
  I opened and poured the contents into a large 3 liter red PET
  jar.  While doing that I thought that the lime in one packet seemed to be 
  slightly darker.

  Put 15 g of that "CaO" in a beaker.  Added 85 g of water.  No heating.
  
  Filtered with 20µm paper. Filtrate clear, pH ~2 (by PHOX PH014).
  
  Since the molar masses of CaO and Ca(OH)2 are 56.1 g and 74.1 g,
  was expecting 19.8 g of Ca(OH)2  on the filter.  But the total 
  weight was 16 g, including 1 g of the paper.  Conclusion:
  it is indeed Ca(OH)2, not CaO!
  
  Removed the top ~1/2 of the contents of the 3 liter PET jar
  into two bowls.  
  
  Repeated the test above with 15 g of the "CaO" that was left 
  in the red jar.  This time, considerable heat was released,
  with swelling.  After filtering, the dry ppt weighted 22 g.
  Seems that it is indeed CaO.
  
  Removed some more contents from the red jar leaving only ~1/3 of
  the initial contents.  Heating and swelling too.  Dry ppt was
  20 g, suggesting some contamination.
  
  
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2017-01-15

  Two of the 3 kg of "cal virgem" that I had bought from Asher, and
  seemed to be partially or totally Ca(OH)2, had been stored for days
  in two plastic bowls.
  
  One of them was suspected to be almost entirely Ca(OH)2, and left
  aside. The other was hoped to be a mixture of CaO and Ca(OH)2. It
  had been covered with majipak and it seemed to have bloated.
  
  I transferred the contents of that second bowl into 4 mason jars
  labeled (1), (2), (3), (4) from top to bottom.  The jars were sealed with 
  masking tape and saved for later analysis.
  
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2017-01-20

  Tested the contents of pots (1), (2), (3), (4) by placing
  a 20 g sample of each in a beaker and adding water.
  After an hour or so the contents were filtered and the
  ppt dried.
  
    (1) ~21 g
    
    (2) ~23 g
    
    (3) ~23 g
    
    (4) ~22 g
    
  The expected weight was 26.4 g.  Therefore they are all heavily
  mixed with Ca(OH)2, although pots (2) and (3) could still be useful.