Question

State what would you observe and write the chemical equation for the reaction that takes place when sodium hydroxide solution is added to a solution of ferric chloride.

Answer 1

Reaction summary

A reddish-brown precipitate of Ferric hydroxide $\left(\mathrm{Fe}{\left(\mathrm{OH}\right)}_3\right)$ is formed when Sodium hydroxide solution $\left(\mathrm{NaOH}\right)$ is added to a solution of Ferric chloride $\left({\mathrm{FeCl}}_3\right)$. This reaction is an example of double displacement reaction.

Skeletal reaction

${\mathrm{FeCl}}_3\left(\mathrm{aq}\right)+\mathrm{NaOH}\left(\mathrm{aq}\right)\to \mathrm{Fe}{\left(\mathrm{OH}\right)}_3\left(\mathrm{s}\right)\downarrow +\mathrm{NaCl}\left(\mathrm{aq}\right)$

• There are $3$chlorine $\left(\mathrm{Cl}\right)$ atoms on the reactant side, while on the product side, there is $1$chlorine$\left(\mathrm{Cl}\right)$ atom only. To balance chlorine atoms, a coefficient of $3$ must be added in front of $\mathrm{NaCl}$.
• However, by this sodium $\left(\mathrm{Na}\right)$ count on the product side becomes unbalanced. To balance sodium atoms, a coefficient of $3$ must be added in front of $\mathrm{NaOH}$. Through this, all the elements in the reaction become balanced.

Balanced chemical reaction

${\mathrm{FeCl}}_3\left(\mathrm{aq}\right)+3\mathrm{NaOH}\left(\mathrm{aq}\right)\to \mathrm{Fe}{\left(\mathrm{OH}\right)}_3\left(\mathrm{s}\right)\downarrow +3\mathrm{NaCl}\left(\mathrm{aq}\right)$