Question

каким анионом можно определить катионы Al 3+ ,Cu 2+ ,Fe 3+ ,NH 4+ ?

Answer 1

Если все вместе, то ионы ОН- в помощь:
с Al3+ выпадает белый осадок, который растворяется в избытке ОН- -ионов;
с Cu2+ выпадает голубой осадок;
с Fe3+ выпадает бурый осадок;
с NH4+ вылетает резко пахнущий аммиак NH3.

Answer 2

Identification of Cations

To identify cations such as Al^3+, Cu^2+, Fe^3+, and NH4^+, various anions can be used in chemical tests.

1. Hydroxide Anion (OH^-)

- Aluminum (Al^3+): When hydroxide ions are added to a solution containing Al^3+ ions, a white gelatinous precipitate of aluminum hydroxide, Al(OH)3, is formed. This reaction can be used to confirm the presence of Al^3+ ions in a solution.

- Copper (Cu^2+): The addition of hydroxide ions to a solution containing Cu^2+ ions results in the formation of a blue precipitate of copper hydroxide, Cu(OH)2. This reaction is a characteristic test for the presence of Cu^2+ ions.

- Iron (Fe^3+): When hydroxide ions are added to a solution containing Fe^3+ ions, a reddish-brown precipitate of iron(III) hydroxide, Fe(OH)3, is formed. This reaction is used to identify the presence of Fe^3+ ions in a solution.

2. Sulfide Anion (S^2-)

- Ammonium (NH4+): When sulfide ions are added to a solution containing NH4+ ions, ammonia gas is released, and a white precipitate of ammonium sulfide, (NH4)2S, is formed. This reaction is used to confirm the presence of NH4+ ions in a solution.

These chemical tests are commonly used in qualitative analysis to identify the presence of specific cations in solution.