Which of the following equations represents the precipitation reaction that occurs when solutions of ammonium chloride and iron(III) nitrate are mixed?

• A. Fe(OH)3(s) forms as a precipitate.
• B. FeCl3(s) forms as a precipitate.
• C. No precipitation occurs.
• D. NH4NO3(s) forms as a precipitate.

Answer: (A)

Verified step by step guidance

1. Identify the ions present in the solutions: Ammonium chloride (NH4Cl) dissociates into NH4^+ and Cl^- ions, while iron(III) nitrate (Fe(NO3)3) dissociates into Fe^3+ and NO3^- ions.
2. Consider the possible combinations of cations and anions that could form precipitates: NH4^+ with NO3^-, NH4^+ with Cl^-, Fe^3+ with Cl^-, and Fe^3+ with NO3^-.
3. Use solubility rules to determine which combinations could form a precipitate: Most nitrates (NO3^-) and ammonium (NH4^+) compounds are soluble, so NH4NO3 and NH4Cl are soluble. FeCl3 is also soluble in water.
4. Recognize that Fe^3+ can react with OH^- ions (from water or other sources) to form Fe(OH)3, which is insoluble and forms a precipitate.
5. Conclude that the precipitation reaction involves the formation of Fe(OH)3(s) as a precipitate when Fe^3+ ions react with OH^- ions in the solution.