FeCl3 (aq) undergoes a double displacement reaction with Ba(OH)2 (aq). If this reaction produces a solid product containing iron, and the other product is in an aqueous solution, what's the balanced chemical equation for this chemical reaction? Briefly explain how to arrive at the balanced reaction equation.

Answer 1

To balance the double displacement reaction between iron(III) chloride (FeCl₃) and barium hydroxide (Ba(OH)₂), we first identify the products of the reaction. The reagents are both soluble in water (forming aqueous solutions), and we expect one of the products to be a solid (precipitate) and the other to remain in solution.

1. Identify the reactants and their ions:

   • FeCl₃ dissociates into Fe³⁺ and 3 Cl⁻ ions.
   • Ba(OH)₂ dissociates into Ba²⁺ and 2 OH⁻ ions.

2. Determine the products:

   • When mixed, the barium ions (Ba²⁺) and chloride ions (Cl⁻) will form barium chloride (BaCl₂), which remains in solution.
   • The iron ions (Fe³⁺) combine with hydroxide ions (OH⁻) to form iron(III) hydroxide (Fe(OH)₃), which is insoluble in water and hence precipitates out as a solid:

   \[ \text{Fe}^{3+} + 3 \text{OH}⁻ \rightarrow \text{Fe(OH)}₃ (s) \]

3. Write the products: Therefore, the products of the reaction based on the ions formed are:

   • Barium chloride (BaCl₂) in aqueous solution and iron(III) hydroxide (Fe(OH)₃) as a solid.

4. Write the unbalanced equation:

   \[ \text{FeCl}_3 (aq) + \text{Ba(OH)}_2 (aq) \rightarrow \text{Fe(OH)}_3 (s) + \text{BaCl}_2 (aq) \]

5. Balance the equation: The unbalanced equation can be balanced to ensure the number of each type of atom on the reactants side equals that on the products side.

   • Count the elements:
     • Reactants: Fe (1), Cl (3), Ba (1), O (2), H (2)
     • Products: Fe (1), Cl (2 from BaCl₂), Ba (1), O (3 from Fe(OH)₃), H (3 from Fe(OH)₃)

   To balance the chlorine atoms, we add a coefficient of 3 to BaCl₂ since FeCl₃ has 3 chloride ions:

   \[ \text{FeCl}_3 (aq) + \text{Ba(OH)}_2 (aq) \rightarrow \text{Fe(OH)}_3 (s) + 3 \text{BaCl}_2 (aq) \]

   Now we rewrite the final balanced reaction:

   \[ 2 \text{FeCl}_3 (aq) + 3 \text{Ba(OH)}_2 (aq) \rightarrow 2 \text{Fe(OH)}_3 (s) + 3 \text{BaCl}_2 (aq) \]

In conclusion, after finding the products and ensuring all atoms are balanced, we arrive at the final balanced equation:

\[ 2 \text{FeCl}_3 (aq) + 3 \text{Ba(OH)}_2 (aq) \rightarrow 2 \text{Fe(OH)}_3 (s) + 3 \text{BaCl}_2 (aq) \]

This equation reflects the conservation of mass, with the appropriate stoichiometric coefficients ensuring that all elements are balanced on both sides of the equation.