The following pictures represent solutions of three salts NaA (A- = X-, Y-, or Z-); water molecules and Na+ ions have been omitted for clarity.

(c) Which A- anion has the smallest value of pKb?

검증된 단계별 안내

Identify the anions in each solution: HA (KC), OH- (KD), and A- (KE).

Recall that pKb is a measure of the basicity of an anion; a smaller pKb indicates a stronger base.

Observe the number of OH- ions in each solution, as they indicate the extent of the reaction A- + H2O -> HA + OH-.

Compare the concentration of OH- ions in each solution: more OH- ions suggest a stronger base and thus a smaller pKb.

Determine which solution has the most OH- ions, indicating the anion with the smallest pKb.

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주요 개념

질문에 올바르게 답하기 위해 반드시 이해해야 하는 핵심 개념들은 다음과 같습니다.

pKb and Basicity

pKb is a measure of the basicity of a base in solution, representing the equilibrium constant for the reaction of the base with water to form hydroxide ions. A lower pKb value indicates a stronger base, meaning it more readily accepts protons. Understanding pKb is essential for comparing the basicity of different anions, as it directly relates to their ability to deprotonate water and generate hydroxide ions.

Anion Types and Their Properties

Anions can vary significantly in their chemical properties and behavior in solution. For instance, anions like OH- are strong bases, while others may be weaker. The nature of the anion affects its interaction with water and its ability to influence the pH of the solution. Recognizing the characteristics of the anions in the question (HA, OH-, and A-) is crucial for determining which has the smallest pKb.

Equilibrium and Acid-Base Reactions

Acid-base reactions involve the transfer of protons (H+) between species, establishing an equilibrium between acids and their conjugate bases. The position of this equilibrium is influenced by the strength of the acids and bases involved, which is quantified by their respective pKa and pKb values. Understanding this equilibrium helps in predicting the behavior of the anions in the solutions and their relative basicity.

The following pictures represent solutions of three salts NaA (A- = X-, Y-, or Z-); water molecules and Na+ ions have been omitted for clarity.(c) Which A- anion has the smallest value of pKb?