Question

Identify each salt as neutral, acidic, or basic. a) \(\mathrm{KC}_{2} \mathrm{H}_{3} \mathrm{O}_{2}\) b) \(\mathrm{KHSO}_{4}\) c) \(\mathrm{KClO}_{3}\)

Short answer

a) Basic, b) Acidic, c) Neutral

Step-by-step solution

Review the Composition of Each Salt

Salt compounds are composed of a cation (positive ion) and an anion (negative ion). The chemical properties of the associated acid or base from which these ions are derived can determine the salt's behavior in aqueous solutions.

Analyze Salt a) \(\mathrm{KC}_{2} \mathrm{H}_{3} \mathrm{O}_{2}\)

\(\mathrm{KC}_{2} \mathrm{H}_{3} \mathrm{O}_{2}\) consists of the potassium ion \(\mathrm{K}^+\) and the acetate ion \(\mathrm{C}_{2} \mathrm{H}_{3} \mathrm{O}_{2}^-\). Potassium hydroxide (\(\mathrm{KOH}\)) is a strong base, and acetic acid (\(\mathrm{HC}_{2} \mathrm{H}_{3} \mathrm{O}_{2}\)) is a weak acid. Since the conjugate base of a weak acid (acetate ion) is stronger than the cation's effect, \(\mathrm{KC}_{2} \mathrm{H}_{3} \mathrm{O}_{2}\) is a basic salt.

Analyze Salt b) \(\mathrm{KHSO}_{4}\)

\(\mathrm{KHSO}_{4}\) contains the potassium ion \(\mathrm{K}^+\) and the hydrogen sulfate ion \(\mathrm{HSO}_{4}^-\). \(\mathrm{KOH}\) is a strong base while sulfuric acid (\(\mathrm{H}_2\mathrm{SO}_4\)) is a strong acid. The \(\mathrm{HSO}_{4}^-\) ion can further donate a proton, making the solution slightly acidic. Therefore, \(\mathrm{KHSO}_{4}\) is an acidic salt.

Analyze Salt c) \(\mathrm{KClO}_{3}\)

\(\mathrm{KClO}_{3}\) is composed of the potassium ion \(\mathrm{K}^+\) and the chlorate ion \(\mathrm{ClO}_{3}^-\). Potassium hydroxide (\(\mathrm{KOH}\)) is a strong base, and chloric acid (\(\mathrm{HClO}_{3}\)) is a strong acid, and neither ion significantly affects the pH. Thus, \(\mathrm{KClO}_{3}\) is a neutral salt.

Key concepts

Acidic Salt

Acidic salts arise when a strong acid partially neutralizes a weaker base. This means that they can donate protons ( H^+ ) when dissolved in water, causing the solution to be slightly acidic. A good example is potassium hydrogen sulfate ( KHSO_4 ). In this compound, the hydrogen sulfate ion ( HSO_4^- ) is capable of releasing a proton, further contributing to the acidic nature of the solution.

• The original strong acid, sulfuric acid ( H_2SO_4 ), still has an acidic character even after the first proton is lost, which results in an overall acidic solution.
• Acidic salts are important in various chemical reactions, especially those involving buffering of solutions.

Understanding the concept of acidic salts is crucial in predicting how they influence the pH of a solution upon dissolving. This is vital in many real-world applications, such as water treatment and pharmaceuticals, where maintaining the correct pH is essential.

Basic Salt

Basic salts are formed when a strong base neutralizes a weaker acid, which results in a solution that is slightly basic when the salt is dissolved in water. Potassium acetate ( KC_2H_3O_2 ) is a typical basic salt. It originates from the reaction of potassium hydroxide ( KOH ), a strong base, with acetic acid ( HC_2H_3O_2 ), a weak acid.

• The acetate ion ( C_2H_3O_2^- ) acts as a stronger base, facilitating the acceptance of protons and thus increasing the pH of the solution.
• Basic salts are often employed in buffering systems to maintain a stable pH environment.

The alkaline nature of basic salts makes them essential in processes such as soap making and the stabilization of solutions in biochemical applications. Recognizing how basic salts behave in water helps us understand their role in chemical equilibria and industrial practices.

Neutral Salt

Neutral salts are unique in that they result from the neutralization between a strong acid and a strong base, with neither the cation nor the anion significantly affecting the pH of the solution. Potassium chlorate ( KClO_3 ) provides a classic case as it consists of ions derived from potassium hydroxide ( KOH ), a strong base, and chloric acid ( HClO_3 ), a strong acid.

• Because both the acid and the base are strong, they completely dissociate in water, and the resulting ions ( K^+ and ClO_3^- ) have no significant impact on the hydrogen or hydroxide ion concentration in the solution.
• Neutral salts maintain a pH close to 7, making them ideal for situations where the neutral pH needs to be preserved.

Understanding neutral salts is fundamental for various scientific and industrial processes, such as in the synthesis of other chemical compounds and in maintaining neutral solutions for biological and chemical testing.