Question

What will happen if we add Mg powder to a (NH4)2SO4(aq) solution?
What would be the products?

DrBob222
In cold water I don't think anything would happen.
Shenaya
In hot water?
DrBob222
In hot water the Mg reacts to form Mg(OH)2 and H2 gas. In strong basic environments ammonium salts decompose to NH3. I don't think Mg(OH)2 is strong enough to cause complete decomposition of (NH4)2SO4 but probably some odor of NH3 could be detected if the reaction is allowed to go long enough to produce sufficient Mg(OH)2. If you ever do this remember that Mg metal is so reactive that it forms a thin coating of MgO on its surface and the reaction with hot water is muted. It is best to scrape that MgO coating off first so you get a rxn with H2O. Al metal does the same thing. In reality, both Mg and Al "rust" but that coating stays on the surface and makes those metals stable. Unfortunately, Fe forms the coating BUT it flakes off, a new surface gets exposed, and it continues to rust until all of the Fe is gone. No extra charge for all of this other interesting chemical information. :-)
Shenaya
Thank you very much! :D
I'll keep that in mind for sure!
Kwikiriza
what is oxidation?