Chemical Forums
Chemistry Forums for Students => High School Chemistry Forum => Topic started by: J-Mart on March 18, 2008, 09:52:31 PM
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I am given a solution of .1M Ammonium Nitrate and asked to calculate the pH. I do not know how to even really begin in dissociating it down into ions. Here's what I know:
NH4NO3(aq) --> N2O(g) + H2O(l)
H2O <==> H+ + OH-
I don't really know how to pull it all together or if I am even on the right track.
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No, not quite on the right track.
NH4NO3 --> NH4+ + NO3-
which one of these ions will affect pH?
then check this out
http://www.chembuddy.com/?left=pH-calculation&right=pH-salt-solution
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Actually when AmoniumNitrate is heated up you will get N2O and 2H20
NH4NO3 ----> N20 +2H2O
If I am Wrong Please tell me?? and State youre reason
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It decomposes - slowly. You will have plenty of time to measure pH :)
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Actually when AmoniumNitrate is heated up you will get N2O and 2H20
NH4NO3 ----> N20 +2H2O
If I am Wrong Please tell me?? and State youre reason
This is out of subject (frankly saing, a very narrow temperature range is needed).
Use Ka of NH4+
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You were wrong ! When we heat the solution of ammonium Nitrate , there will be exist the equation that NH4NO3 --> N2O + H2O
In the water , NH4NO3 is dissolved into NH4+ and NO3-
There is a reversible equation :
NH4+ <=> NH3 + H+ Ka
and then we have a solution for this problem .
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You were wrong ! When we heat the solution of ammonium Nitrate , there will be exist the equation that NH4NO3 --> N2O + H2O
In the water , NH4NO3 is dissolved into NH4+ and NO3-
There is a reversible equation :
NH4+ <=> NH3 + H+ Ka
and then we have a solution for this problem .
when we heat solution, nothing is happen. For thermal decomposition we need higher temperature
What des mean this eqution?
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You were wrong !
Who "you"? 5 people posted earlier in this thread.
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Well NO3- does not react with water (dissolve in water i mean, or ionize in water, Actually i am new one here and i am not adapted with english words of Chemistry) because the conjugative(συζυγες for those who are Greek) acid is strong
So
NH4NO3 ->NH4+ + NO3-
goes to
NH4- + H2O -> NH3 + H3O+
If we know Kb of NH3 which is i think 10-5
with Kw we have Ka=Kw/Kb
If it's 25oC Kw=10-14 so Ka=10-9
Ka=[NH3][H3O+]/[Nh4+]
then
[NH3]=[H3O+]=x
[Nh4+]= C-x=1-x
so
10-9=x2/1-x
Ka/C<0,01 so from the approximate calculation we have:
10-9=x2
PH=5-1/2log10=4,5
Is that solution ok. I tried to be complete...
(By the way Hi Everyone!)
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Well NO3- does not react with water (dissolve in water i mean, or ionize in water, Actually i am new one here and i am not adapted with english words of Chemistry) because the conjugative(συζυγες for those who are Greek) acid is strong
In general - you are right. For the nitpickers, nitric acid is the weakest of strong acids, with pKa=-1.
Your approach seems correct, just Kb of ammonia is 1.8x10-5.
Please read forum rules (http://www.chemicalforums.com/index.php?page=forumrules) (especially Answering Questions section).
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Nh4+]= C-x=1-x
The concentration of ammonium nitrate is 0.1, not 1 M.
pH of 0.1 M NH4NO3 is about 4.1 (pH of 1 M - about 4.6)