Question

At a concentration of 1 M, the weak acid HNO2 is 2% ionized and the pH of the solution is 1.7. What happens when KNO2(s) is dissolved into the solution?

Answer 1

Based on your question where there is a concentration of 1 M, the weak acid HN02 is 2% ionized nad the PH of the solution is 1.2. The possibilities that could happen to KNO2(s) if it will dissolved into the solution is that when more nitrite is added to the solution, the reaction will shift towards the reactants because of La Châtelier's principle. In doing this, the solution will decrease in hydronium concentration and therefore the pH will increase by some amount.

Answer 2

Answer:

Explanation:

Weak acids, as in this case, are characterized by partially dissociating in solution. Each ionization equilibrium associated with a constant, K. This parameter allows evaluating the concentrations corresponding to the species in the equilibrium. In this case the reaction is ionization by the following equation:

HNO₂ ⇔ H⁺ + NO₂⁻

The Le Chatelier Principle states that if a system in equilibrium undergoes a change in conditions, that is, variations in experimental conditions occur, the equilibrium will shift to a new position (towards reagents or products)  in order to recover the state of equilibrium.

In this case KNO₂ is added, then NO₂⁻ ions are being added. In this way, its concentration increases. If you observe the dissociation reaction, you can see that adding KNO₂ increases the concentration of the NO₂⁻ product.

Following the principle of Le Chatelier, by increasing the concentration of a substance in a chemical equilibrium, the system responds by opposing said increase. That is, the equilibrium will shift in the sense that the concentration of that substance decreases.  As in this case the concentration of the NO₂⁻ product increases, the equilibrium shifts towards the reagents in the dissociation reaction.

In this way and taking into account that the degree of ionization is the amount of the dissociated substance, the extend of HNO₂ ionization  decreases, and in turn the concentration of  H⁺ will decrease.

Since pH = −log [H +], as the concentration of H + decreases, the pH will also decrease.