Question

Lake test of $A{l}^{3+}$ ion is based on adsorption of blue litmus on solid surface of:

• A. $Al$
• B. $Al(OH{)}_3$
• C. $A{l}_2{O}_3$
• D. $AlC{l}_3$

Answer 1

Answer: (B)

$Al(OH{)}_3$

Lake test of $A{l}^{3+}$ ion is based on adsorption of blue litmus on the solid surface of $Al(OH{)}_3$. The dye aluminon is adsorbed by the gelatinous $Al(OH{)}_3$ precipitate to form lake colored solution.

This test is used as a confirmatory test for $A{l}^{3+}$ after precipitation of $Al(OH{)}_3$ with aqueous ammonia.