Question

Write the Ka expression for an aqueous solution of nitrous acid: (Note that either the numerator or denominator may contain more than one chemical species. Enter the complete numerator in the top box and the complete denominator in the bottom box. Remember to write the hydronium ion out as H3O+ , and not as H+ )

Answer 1

Answer:

$Ka=\frac{[NO_{2}^{-}][H_{3}O^{+} ]}{[HNO_{2}]}$

Explanation:

Let's consider the acid dissociation of nitrous acid in water.

HNO₂(aq) + H₂O(l) ⇄ NO₂⁻(aq) + H₃O⁺(aq)

The acid dissociation constant (Ka) is the product of the concentration of the products raised to their stoichiometric coefficients divided by the product of the concentrations of the reactants raised to their stoichiometric coefficients. It does not include solids or pure liquids (H₂O(l) in this case).

$Ka=\frac{[NO_{2}^{-}][H_{3}O^{+} ]}{[HNO_{2}]}$