Which of the following mixtures can be separated by using excess NH3 solution? — Qualitative and Quantitative Analysis Chemistry Question

💡 Solution & Explanation

Al3+ and Zn2+ both form white ppt. with NH3 solution but white ppt. of Zn(OH)2 is soluble in excess of NH3. Al3+ + 3NH3 + 3H2O -> Al(OH)3↓ (no reaction with excess). Zn2+ + 2NH3 + 2H2O -> Zn(OH)2↓ (forms soluble [Zn(NH3)4]2+ in excess).