This chemistry question involves key chemical concepts and calculations. The detailed solution below walks through each step, from identifying the reaction type to computing the final answer.
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To determine which ion will give a solution with pH < 7 (acidic), we need to consider the hydrolysis of each ion in water. Step 1: Analyze the nature of each ion. • A. Na^+: This is the conjugate acid of a strong base (NaOH). Ions from strong bases do not hydrolyze significantly in water, so they do not affect the pH. • B. NH_4^+: This is the conjugate acid of a weak base (NH_3). Conjugate acids of weak bases are acidic and will react with water to produce H_3O^+ ions. • C. CN^-: This is the conjugate base of a weak acid (HCN). Conjugate bases of weak acids are basic and will react with water to produce OH^- ions. • D. HCOO^-: This is the conjugate base of a weak acid (formic acid, HCOOH). Similar to CN^-, it will react with water to produce OH^- ions. Step 2: Write the hydrolysis reaction for the ion that would produce an acidic solution. An acidic solution has a pH less than 7, meaning it has an excess of H_3O^+ ions. From Step 1, NH_4^+ is the only ion that is an acidic conjugate. The hydrolysis reaction for NH_4^+ is: NH_4^+ (aq) + H_2O (l) NH_3 (aq) + H_3O^+ (aq) This reaction produces hydronium ions (H_3O^+), which makes the solution acidic, resulting in a pH less than 7. The other ions would either not affect the pH (Na^+) or make the solution basic (CN^- and HCOO^-). The correct option is B. B. NH_4^+ Send me the next one 📸