Chemistry Forum

Hi I wonder if anyone can help me and give me the reactions of formation of ammonium alum thanks.

skinmsn wrote:Hi I wonder if anyone can help me and give me the reactions of formation of ammonium alum thanks.

Ammonium aluminium sulfate is produced from ammonium sulfate, aluminium(III) hydroxide, and sulfuric acid:

1 (NH4)2SO4 + 2 Al(OH)3 + 3 H2SO4 => 2 (NH4)Al(SO4)2 + 6 H2O

or by mixing solutions of (NH₄)₂SO₄ and Al₂(SO₄)₃
-dissolve the sulfates in least amount of water at higher temperature, mix the solutions and let it cool and crystalize

thanks but i forgot write that the reactives are Al₂(SO₄)₃+NH₃, or +NH₄(OH)

ill be grateful if you can help me...

The same principle applies. You'll also require sulfuric acid to balance the sulfate anions with ammonium and aluminium cations; and to neutralise the hydroxide anions.

Al2(SO4)3 + 2 NH4OH + H2SO4 => 2 NH4Al(SO4)2 + 2 H2O

Or equivalently: (Since NH3 + H2O = NH4OH.)

Al2(SO4)3 + 2 NH3 + H2SO4 => 2 NH4Al(SO4)2


Well, that's the overall equation. Of course, you might actually want to do it in a two step process. First, produce ammonia sulfate by exposing hot sulfuric acid to ammonia gas. Then mix the product with aluminium sulfate as suggested above.