FeCl3 + NaOH ? Fe(OH)3 + NaCl
The Correct Answer and Explanation is:
The balanced chemical equation for the reaction between iron(III) chloride (FeCl₃) and sodium hydroxide (NaOH) is:
FeCl₃ + 3NaOH → Fe(OH)₃ + 3NaCl
Explanation:
This reaction is an example of a precipitation reaction. In this case, iron(III) chloride (FeCl₃), a soluble salt, reacts with sodium hydroxide (NaOH), a strong base, to form iron(III) hydroxide (Fe(OH)₃) and sodium chloride (NaCl), a soluble salt.
- Iron(III) chloride (FeCl₃) is composed of iron ions (Fe³⁺) and chloride ions (Cl⁻).
- Sodium hydroxide (NaOH) dissociates into sodium ions (Na⁺) and hydroxide ions (OH⁻) when dissolved in water.
When these two substances react, the hydroxide ions (OH⁻) from NaOH react with the iron ions (Fe³⁺) from FeCl₃ to form iron(III) hydroxide (Fe(OH)₃), which is insoluble in water. This forms a precipitate. The chloride ions (Cl⁻) from FeCl₃ pair with the sodium ions (Na⁺) from NaOH to form sodium chloride (NaCl), which remains dissolved in the solution.
Why is iron(III) hydroxide (Fe(OH)₃) formed as a precipitate?
Iron(III) hydroxide is insoluble in water, which is why it precipitates out of the solution as a solid. The insolubility of iron(III) hydroxide is a key characteristic of many transition metal hydroxides.
Stoichiometry:
To balance the equation, note that for each Fe³⁺ ion in FeCl₃, three OH⁻ ions are needed to form Fe(OH)₃. Therefore, the coefficient for NaOH is three, resulting in the balanced equation:
FeCl₃ + 3NaOH → Fe(OH)₃ + 3NaCl
This reflects the stoichiometric relationship between the reactants and products.
