Which of the following reagents can be successfully utilized to distinguish between and ions present — Qualitative and Quantitative Analysis Chemistry Question

💡 Solution & Explanation

All four reagents can distinguish the two ions. $K_4[Fe(CN)_6]$ gives a white/light blue ppt with $Fe^{2+}$ but an intense Prussian blue with $Fe^{3+}$. $K_3[Fe(CN)_6]$ gives Turnbull's blue with $Fe^{2+}$ but a brown coloration with $Fe^{3+}$. $NH_4SCN$ gives a blood-red coloration with $Fe^{3+}$ but no characteristic color with $Fe^{2+}$. DMG gives a red soluble complex with $Fe^{2+}$ in an alkaline medium but does not produce this with $Fe^{3+}$.