# NCl₃ + H₂O → NH₃ + HOCl , the resulting solution is acidic, basic or neutral?

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!

• Try balancing the equation. What do you notice? – Nicolau Saker Neto Jun 14 '14 at 12:28
• 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. – permeakra Jun 14 '14 at 19:15

## 2 Answers

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.

• What's the extent of these reactions? – Dissenter Jun 14 '14 at 16:29
• 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. – ron Jun 14 '14 at 16:50
• 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. – Dissenter Jun 14 '14 at 18:46
• 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. – ron Jun 14 '14 at 19:22
• 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. – Dissenter Jun 14 '14 at 19:24

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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