When #HNO_2# is titrated with #NaOH# to the equivalence point is the pH of the resulting solution greater than, less than or equal to seven?

1 Answer
May 15, 2017

Answer:

#pH# should be GREATER than #7#.........Why?

Explanation:

At the equivalence point, we have a solution that is stoichiometric in #NaNO_2(aq)#. Now #NO_2^-# is the conjugate base of a fairly weak acid; in effect, this means that the conjugate base competes relatively strongly for the proton, and thus AT EQUIVALENCE, the following equilibrium occurs to some extent:

#""^(-)NO_2(aq) +H_2O rightleftharpoons HNO_2(aq) + HO^-#

We could work the #pH# out quantitatively if we had the concentration of #NaNO_2# and #pK_a# for #"nitrous acid"#. Given that #HO^(-)>10^-7*mol*L^-1#, #pH>7#, and a BASIC solution is specified.

If you are clear on what I have argued, well and good. If no, ask away and someone will help you.