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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?

Answer 1

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

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.

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Answer 2

Jose Ayala

The pH of the resulting solution at the equivalence point of titrating HNO2 with NaOH is greater than 7.

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Answer from HIX Tutor

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.