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       #Post#: 111--------------------------------------------------
       Problem of the Week- 29/4/12
   DIR By: Michel
       Date: May 1, 2012, 5:26 pm
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       The equation for the reversible reaction of bismuth trichloride
       with water is
       BiCl3(aq) + H2O<--->BiOCl(s) + 2H+  + 2Cl-
       i) When the reaction  goes from left to right, what would you
       expect to see?
       ii)Explain why it is impossible to prepare a clear solution of
       bismuth trichloride by adding some solid to pure water
       iii)What would be the effect of adding dilute HCl to the mixture
       at equilibrium?
       iv)What would be the effect of adding solid sodium hydroxide to
       the mixture at equilibrium and stirring so that it dissolves.
       v)What gas will be evolved if the BiOCl is mixed with a strong
       mineral acid?
       I'll try to be consistent with these problems, but trying to
       solve them would help a great deal;-)
       #Post#: 2197--------------------------------------------------
       Re: Problem of the Week- 29/4/12
   DIR By: Potla
       Date: February 25, 2013, 6:53 am
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       Let me give it a try, although it's been almost 10 months
       already. :P
       i) Well, it's the well-known cloudy white ppt which confirms the
       presence of Bi3+.
       ii) The more water you add, the reaction moves more in the
       forward direction, so the solution becomes less transparent.
       iii) Adding dil. HCl would move the equilibrium leftwards, so
       that the hydrolysis of BiCl3 will be reduced, and the solution
       will get more transparent.
       iv) Adding NaOH will move the reaction to the right, giving more
       of the ppt.
       v) BiOCl should react with mineral acids to liberate HCl,
       although I am not sure.
       Please let me know if I slipped off somewhere. :)
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