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When $\ce{NCl3}$ is dissolved in water, $\ce{NH3}$ and $\ce{HOCl}$ is formed.

Can you please explain me whether formed solution is acid or basic or neutral? thank you!

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    $\begingroup$ Try balancing the equation. What do you notice? $\endgroup$ Jun 14, 2014 at 12:28
  • $\begingroup$ You should specify initial concentrations. generally, your question has no simple 'qualitative' answer, as both acid and base produced are weak. However, analytical chemistry textbooks should have an entire section about calculation of pH of similar solutions. $\endgroup$
    – permeakra
    Jun 14, 2014 at 19:15

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Here's our initial reaction, $$\ce{NCl3 + 3H2O -> NH3 + 3HOCl}$$ $\ce{NH3}$ is a weak base and $\ce{HOCl}$ is a weak acid, but there is more of the acid, so at this point the solution would be mildly acidic. However $\ce{NH3}$ and $\ce{HOCl}$ are known to react as follows $$\ce{NH3 + HOCl->NH2Cl + H2O}$$ and in aqueous solution the resultant chloramine can decompose as shown in the following equation $$\ce{3 NH2Cl ⟶ N2 + NH4Cl + 2 HCl}$$ Clearly, an acid is generated in this last reaction. So although the initial products are neutral, eventually the solution will be strongly acidic.

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  • $\begingroup$ What's the extent of these reactions? $\endgroup$
    – Dissenter
    Jun 14, 2014 at 16:29
  • $\begingroup$ I suspect they all move further to the right with time - the ammonia escapes or is consumed, the chloramine decomposes or reacts further, just a guess. Open or closed containers would make a difference in the rates. $\endgroup$
    – ron
    Jun 14, 2014 at 16:50
  • $\begingroup$ I was wondering because the extents can affect whether the solution is actually mildly acidic, strongly acidic, or not acidic at all. Strongly acidic implies that the third reaction goes forward to a large extent. $\endgroup$
    – Dissenter
    Jun 14, 2014 at 18:46
  • $\begingroup$ Good point. But you'd be a tough professor. The OP's teacher just wanted to know acidic, basic or neutral; you're drilling down to not, mildly or strongly acidic :) I would guess that the third reaction goes far to the right as the nitrogen leaves the liquid phase, just don't know the timescale. $\endgroup$
    – ron
    Jun 14, 2014 at 19:22
  • $\begingroup$ What about this reaction? NH3 + HOCl -> NH4+ + ClO-? This reaction would be large extent, and would probably consume a fair bit of the ammonia and hypochlorous acid. $\endgroup$
    – Dissenter
    Jun 14, 2014 at 19:24
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It is less but acidic since in HOCl, OH bond dissociates to form proton.Though NH3 is a lewis base,it is not strong enough to neutralize the acidic HOCl.

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  • $\begingroup$ Consider coming over here. You might be interested since there are Indian highschool students out there. $\endgroup$
    – user223679
    May 20, 2015 at 7:55

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