Magnesium + water = ???

[itch vaccine]

Hi,

My chemistry needs help.

This seems like a very simple question, and I was told it should be Mg(OH)2 -- Magnesium hydroxide

Okay, now this is the case.
I have a revision book which states that Magnesium Hydroxide should form when Magnesium reacts with water. I have my teacher's notes which states the same time.

I also have my textbook which says that Magnesium does not form the normal hydroxide, but reacts with water to form Magnesium Oxide --- MgO.

Okay... -.-''
So now .. is it oxide or hydroxide.

Thank you so much

[phukraut]

According to Kotz & Treichel (3rd ed.),

Mg(s) + 2H_2O(l) --> Mg(OH)_2(s) + H_2(g) + heat.

On the other hand,

2Mg(s) + O_2(s) --> 2MgO(s).

I haven't taken chemistry in years, so I'm not certain why

Mg(s) + H_2O(l) --> MgO(s) + H_2(g)

doesn't work, but I have a feeling it has to do with the energy involved in the reaction.

[vinaur]

Even if Mg in water yields MgO, it will then turn to Mg(OH)2, because a metal oxide in water yields a base (all of them do), so at the end you still have Mg(OH)2.

[Seanland]

Originally Posted by phukraut

According to Kotz & Treichel (3rd ed.),

Mg(s) + 2H_2O(l) --> Mg(OH)_2(s) + H_2(g) + heat.

From what I remember from Chemistry, this is probably the one your thinking off.. cause, when you do physically do this (which I have ).. the magnesium glows from the heat it gives off, releases a gas, and leaves crap in the container, so I'm almost certain that this is the right reaction

[Slavakion]

Under normal circumstances, it forms the hydroxide. Just dip it in some water and you'll see the H2 evolving from it.

[Hain]

Originally Posted by vinaur

Even if Mg in water yields MgO, it will then turn to Mg(OH)2, because a metal oxide in water yields a base (all of them do), so at the end you still have Mg(OH)2.

Yes it seems you learned the MOWB (Metal Oxide plus Water yields Base) and NOWA (Nonmetal Oxide plus Water yields Acid). But yes that is what happens

Mg(aq) + 2H20(l) --> Mg(OH)2(aq) + H2(g)

[tman17m]

= fun

well, i know that if you put a block of it in water it will ignite...pretty cool
my chem knowladge is horrible, but ask me something about electrical engineering and ive got you covered

[itch vaccine]

Originally Posted by vinaur

Even if Mg in water yields MgO, it will then turn to Mg(OH)2, because a metal oxide in water yields a base (all of them do), so at the end you still have Mg(OH)2.

Oh yeah good point Vinaur

teacher said :
Cold water = slow reaction.. MgO forms

Hot water = fast reaction Mg(OH)2 forms