# Last edited on 2017-02-24 05:50:26 by jstolfi

PREPARING STANDARD SOLUTIONS OF CALCIUM CHLORIDE

  Calcium chloride CaCl2 has many hydrated forms. 
  
  Its solubility in water is anomalous: it is concave 
  up to 20 C, convex above 30 C.  Between 20 C and 30 C
  there is a sharp increase, not well documented it seems.

  Solubility of anhydrous CaCl2 in H2O (in g per 100 ml):
  See gawklib/fill_water_solubility_table_CaCl2.gawk
    
  Molar mass of CaCl2: 111 g

----------------------------------------------------------------------
2016-??-??

  Bad experience when preparing CuCl2 from CaCl2 and CuSO4: A hot
  concentrated solution of CaCl2 was left to cool in a 600 ml beaker.
  Next morning the CaCl2 had crystallized into a dry solid mass, and the
  expansion cracked the beaker.

----------------------------------------------------------------------
2016-12-12

  A reagent solution of CaCl2 for later use was prepared by filtering the
  contents of a spent Inspira dehumidifier pot, which had completely
  liquefied. The filtrate (Cx) was stored in an amber bottle with stopper.
  
----------------------------------------------------------------------
2016-12-23

  Put ~90 g of solid CaCL2.(H2O)x [Asher] in beaker. Added water to ~100 ml.
  Solution (Cz) became hot, to ~50 C).
  
  Added the solution (Cx) from the Inspira box (~ 200 ml more).
  
----------------------------------------------------------------------
2016-12-24

First attempt

  Prepared a solution (C0) of CaCl2, using the previous (Cz). Attempted
  to make it saturated at 40 C (but maybe failed). Solution was slightly
  cloudy; perhaps CaCO3?
  
  Poured 348 g of (C0) into a beaker through a strainer. Completed to
  500 g with water, yielding (C2). Filtered through W201 paper obtaining
  ~380 ml of filtrate (C3), weight ~491 g. (Lost ~7g of solution on
  filter paper.)
  
  Solution was expected to be saturated at 0 C, but did not crystallize
  even at -5 C.  Stored in brown bottle.
  
Second attempt

  Prepared a saturated solution (C4) of CaCl2 at 30 C.
  Poured 128 g into a beaker through a strainer.  Completed with water
  to 150 g yielding (C5).
  
  On cooling, (C5) was found to saturate at 14 C.  Because of losses in filter
  it was 102 ml and weighted 144 g (density 1.41 g/ml).
  
  Interpolating by hand a parabola through the solubility values of
  anhydrous CaCl2 in H2O at 0 C, 10 C, and 20 C, it should be 68.5 g in
  100 ml at 14 C.
  
  So 168.5 g of the solution (C5) contains 100 g H2O and 68.5 g of CaCl2.  
  That is 40.7% CaCl2 by weight. Also 1000 ml of solution would weigh 1412 g
  and contains 574 g CaCl2.  That is 5.17 molar.