Predict the relative pH (greater than 7 , less than 7 ,...

Predict the relative pH (greater than 7 , less than 7 , etc.) for water solutions of the following salts. Table 9.9 may be useful. For each solution in which the pH is greater or less than 7 , explain why and write a net ionic equation to justify your answer. a. Potassium sulfite, $\mathrm{K}_2 \mathrm{SO}_3$ b. Lithium nitrite, $\mathrm{LiNO}_2$ c. Sodium carbonate, $\mathrm{Na}_2 \mathrm{CO}_3$ d. Methylammonium chloride, $\mathrm{CH}_3 \mathrm{NH}_3 \mathrm{Cl}\left(\mathrm{CH}_3 \mathrm{NH}_2\right.$ is a weak base)

Predict the relative pH (greater than 7 , less than 7 , etc.) for water solutions of the following salts. Table 9.9 may be useful. For each solution in which the pH is greater or less than 7 , explain why and write a net ionic equation to justify your answer.
a. Potassium sulfite, $\mathrm{K}_2 \mathrm{SO}_3$
b. Lithium nitrite, $\mathrm{LiNO}_2$
c. Sodium carbonate, $\mathrm{Na}_2 \mathrm{CO}_3$
d. Methylammonium chloride, $\mathrm{CH}_3 \mathrm{NH}_3 \mathrm{Cl}\left(\mathrm{CH}_3 \mathrm{NH}_2\right.$ is a weak base)

Key Concepts

Salt Hydrolysis

Salt hydrolysis is the process by which ions from a dissolved salt react with water to produce either hydronium (H3O+) or hydroxide (OH–) ions, thereby altering the pH of the solution. This concept is crucial in predicting whether a salt solution will be acidic, basic, or neutral based on the acid-base strengths of the ions involved.

Conjugate Acid-Base Pairs

Every acid has a conjugate base and every base has a conjugate acid. The strength of these conjugates plays a key role in determining the pH of a solution. For instance, if a salt’s cation is the conjugate acid of a weak base, its hydrolysis can make the solution mildly acidic, while if the anion is the conjugate base of a weak acid, hydrolysis can render the solution basic.

Weak Acids and Weak Bases

Weak acids and weak bases do not completely dissociate in water, leading to equilibrium conditions that are sensitive to the concentration of their conjugate forms. Understanding the behavior of weak acids and bases is important when predicting the outcome of salt hydrolysis, as the incomplete dissociation provides room for the ions to react with water and influence the overall pH.

Net Ionic Equations

Net ionic equations are simplified chemical equations that display only the species directly involved in a chemical reaction, omitting spectator ions. They are particularly useful in illustrating the hydrolysis reactions that determine the pH of a salt solution, by clearly showing how specific ions interact with water to generate H3O+ or OH–.

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