Aqueous ferric chloride (FeCl3) reacts with aqueous sodium hydroxide (NaOH) to produce ferric hydroxide ( Fe(OH)3 ) and sodium chloride (NaCl). So, yellow-brown color solution will turn into a brown color precipitate. Color changes, precipitating, balanced reaction, ionic equation of FeCl2 + NaOH reaction are discussed in this tutorial.
Ferric chloride ( Iron(III) chloride ) is a soluble inorganic compound in water and form a yellow-brown solution.
Sodium hydroxide is a strong alkaline colorless solution and readily gives hydroxyl ions (OH-).
When we add aqueous NaOH solution to aqueous FeCl3 solution, brown color precipitate is formed. This precipitate is ferric hydroxide ( Fe(OH)3 ).
Above mentioned reaction is not a balanced chemical reaction. So, we need to balance this reaction and we will do it next section.
This reaction is a not a redox reaction. Therefore by observing number of atoms in right side and left side, we can balance the reaction in few seconds. This method is a trial and error method. But it is so easy for like this simple equation.
According to the stoichiometry of the reaction, 1 mol of FeCl3 reacts with 3 mol of NaOH and produce 1 mol of Fe(OH)3 and 3 mol of NaCl.
FeCl3 is soluble in water. Therefore, it exists as an aqueous solution and NaOH also exists as a solution. But, solubility of Fe(OH)3 is poor in water. Hence it deposits as a precipitate at the bottom of the reaction. NaCl is very much soluble in water and exists as an aqueous solution.
There are two aqueous solutions. In one solution, there is 0.1 mol dm-3 FeCl3 0.1 dm3 and other aqueous solution is 0.1 mol dm-3 NaOH2 0.1 dm3. When, these two solutions are mixed with each other, how much grams are precipitated as Fe(OH)3?
Answer: First, you have to find mixed amounts of NaOH and FeCl3.
To react with 0.01 mol FeCl3, 0.03 mol of NaOH is required according to the stoichiometric equation. But, there is only, 0.01 mol of NaOH. Therefore, NaOH is the limited reagent.
Assumption: Amount of Fe(OH)3 in the aqueous phase is negligible compared to amount in the precipitate.
Questions asked by students
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If you add aqueous ammonia solution to the FeCl3 solution, you can see ferric chloride, brown color precipitate is formed.
Fe(OH)2 is not soluble in excess NaOH or aqueous ammonia solution. So brown colour precipitate will remain in the solution.