Question

A mixture of $Al(OH{)}_3$ and $Fe(OH{)}_3$ can be separated by:

• A. $HCl$
• B. $N{H}_{4}OH$
• C. $NaOH$
• D. $HN{O}_3$

Answer 1

The correct option is C $NaOH$

$Fe(OH{)}_3$ is insoluble in aqueous sodium hydroxide solution. Whereas $Al(OH{)}_3$ is soluble in excess of sodium hydroxide. Thus, to separate $Fe(OH{)}_3$ and $Al(OH{)}_3$, aqueous $NaOH$ solution is added. $Al(OH{)}_3$ will dissolve in it whereas $Fe(OH{)}_3$ will remain insoluble. The two can then be separated by filtration.