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

💡 Solution & Explanation

Fe3+ precipitates as Fe(OH)3 which is insoluble in excess NaOH. Al3+ precipitates as Al(OH)3 but dissolves in excess NaOH to form soluble Na[Al(OH)4]. (Note: Pb, Zn, Al, Sn all have amphoteric hydroxides that dissolve in excess NaOH).