[Swift77]

Hi all you Chemistry-Experts out there!
I got a question regarding salts who aren´t neutral like sodiumchloride.
I need to explain why a sour salts actually raises the pH⁺
and an alcalic one creates more hydroxides.

For example giving Silver nitrate in solution
Ag⁺ + H2O -> AgOH + H⁺

This reaction above is much more likely to occur than that one below


NO3^- + H2O -> HNO3 + OH^-

How can describe it correctly using the pKa and pKb´s values which of these is more likely to occur. Nitric Acid is a strong acid but why is this reaction more unstable than that one with the Silverhydroxide?
Could someone explain it for me?
 
Thanks so much in advance

[pathos6296]

I'm not sure what you're quite asking about the second reaction.  I believe you may be referring to it not running to completion.  This is because reactions tend to favor the direction of the weak acid and base.  Here H20 definitely functions as an acid and has a certain pka value.  Remember, the lower the pka value the strong the acid.  However, the pka value of nitric acid is much lower than that of H20, I believe its negative, which means its very strong.  The reaction is going to favor the left side.  Similarly, OH- is a strong base than NO3- which is very weak, since its acid, Nitric acid is very strong.  Remember, acid-conjugate base strength is inversely proportional.

HNO3 + OH-   --> NO3- + H20 is more likely to occur.

[Swift77]

Hi pathos6296
thanks for your great explanation

I'm not sure what you're quite asking about the second reaction.

I listed the second reaction because we should explain why these is much less favored as the one above, explaining it via the pKa - pKb  values.
Yep and you are right. The arrow should be pointing in reverse direction.

But thank you helped a lot ^^