A level H2 chem.

• Coolplay

  5 Nov 09, 22:32

  The solubility products of some Group II fluorides, at 25 oC, are given in the table
  below: 
   
  Numerical values of Ksp
  BaF2  1.84 x 10–7
   CaF2  3.45 x 10–11
   
   
  A student accidentally mixed 25.0 cm3 of 0.100 mol dm–3 CaCl2 solution with 
  25.0 cm3 of 0.100 mol dm–3
   BaCl2 solution in the laboratory. To separate the two
  metal ions, he added just enough solid KF to precipitate the maximum amount of
  CaF2 from the mixture, without precipitating BaF2. 
   
  (i)  Determine the [F–] required for this separation. 
   
  (ii)  Determine the concentration of Ca2+ remaining in the final solution.

   

  (b)  (i) 1.92 x 10–3 mol dm–3
   
   
      (ii) 9.38 x 10–6 mol dm–3
   

  hi, this question im given the answer but i dont know how to arrive at it. need help.

  thanks in advance (:

• UltimaOnline

  5 Nov 09, 23:55

  Note the time of Coolplay's post above. Notice that 6 hours 11 minutes earlier, SBS n SMRT had precognitively predicted Coolplay's post, and had posted the required hints to Coolplay's problem, within my "Collection of Chemistry Qns" thread (scroll to the bottom). http://www.sgforums.com/forums/2297/topics/320107?page=8#posts-9467798 If anyone wants to know what happens to the world in 2012, ask SBS n SMRT to share his prophetic vision of the future.