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Chemistry Forums for Students => Analytical Chemistry Forum => Topic started by: mahtrelew on December 02, 2007, 05:47:13 PM

Title: Reaction NH4OH - NH3Cl
Post by: mahtrelew on December 02, 2007, 05:47:13 PM

I've been asked to find the pH of NH4OH 0.1 M and NH3Cl 0.05 M.
I tried these reactions:

NH4OH <==> NH4 + OH   with Kb=1.8 E 5-   (1)

NH3Cl ---> NH3 + Cl

and then

NH3 + H20 <===> NH4 + OH        (2)

then then the concentration of NH4 and the concentration of OH is the  sum of  NH4 and the sum of OH I carry from (1) and the NH4 and OH due to the reaction (2), and the pH will be

pH=14-pOH of reaction (2).

I'll appreciate you to tell me if that's ok.

Thanks a lot.

Title: Re: Reaction NH4OH - NH3Cl
Post by: Borek on December 02, 2007, 05:57:59 PM

No such thing as NH₃Cl, I suppose you mean NH₄Cl?

Do you mean that solution contains both NH₃ (or NH₄OH, it is the same thing here) and NH₄Cl? If so, it is buffer solution (http://www.chembuddy.com/?left=pH-calculation&right=pH-buffers-henderson-hasselbalch).

Title: Re: Reaction NH4OH - NH3Cl
Post by: mahtrelew on December 02, 2007, 06:02:47 PM

Reading your answer, I guess there was a mistake either when I copied the problem or when the professor wrote it. I'll check. Thanks a lot for your answer.