Question

${Fe\left(OH\right)}_3$ and ${Al\left(OH\right)}_3$ can be separated using :

• A. $NaOH$
• B. $KOH+{Br}_2$water
• C. both (a) and (b)
• D. None of these

Answer 1

The correct option is A $NaOH$

${Fe\left(OH\right)}_3$ is insoluble in excess of NaOH whereas ${Al\left(OH\right)}_3$ is soluble in excess of NaOH.
When ${Al\left(OH\right)}_3$ is boiled with excess of NaOH, soluble sodium meta aluminate is obtained.

${Al\left(OH\right)}_3+NaOH\to \underset{\text{sodium meta aluminate}}{Na\left[Al{O}_2\right]}+2H_{2}O$