Will Mg + H2O -> boom?

[postgrep]

During a chemistry class, I believe the teacher said that exposing Magnesium to water will cause an explosion (or in his words, a large "pop"). Can anyone verify whether it is Magnesium, or am I thinking of Potassium?

[YT2095]

magnesium in water won`t react very much unless you heat the water a little, it will give off Hydrogen gas, that when collected and ignited will make a POP in a test tube or a BOOM in larger vessels.

Potassium metal and water (if uncontained) will catch fire with a purple flame, basicly it reacts with the water very quickly and gives off lots of Hydrogen gas and heat, that heat is enough to ignite the Hydrogen almost instantly.

small quantities of this won`t explode, larger ones or contained ones most certainly will!

[postgrep]

Ah, I understand now. I better pull out my old bunsen burner for some fun!

 

Is there any critical amount of magnesium needed to get a sufficient amount of gas?

[YT2095]

not really, and it`ll be accelerated with the addition of an acid (even just plain vinigar), the idea is to have enough gas to fill a test tube, so maybe quarter gram of Mg and 5 to 10ml of an acid.

you`ll need to keep this mixture upright and have another test tube upside down over the other one (it`ll catch the hydrogen gas).

when you`re satisfied that there`s enough in there, still keeping the top tube upside down, put your thumb over the hole to keep the gas in, then present it to the flame and remove your thumb, you`ll hear a whistle/pop sound, that`s the Hydrogen burning

[jdurg]

You could always light some magnesium on fire and then throw the burning Mg into a pool of water. That would create a pretty impressive reaction as Mg reacts with steam and the burning magnesium would create a lot of steam which would create a good deal of H2.

[olmpiad]

It depends on the amount of Mg and the heat it gets up to in the water. If it heats hot enough to ignite the H released when the Mg is reacting with hot water, than yes, there will be a little "Pop".

[xeluc]

You could always light some magnesium on fire and then throw the burning Mg into a pool of water. That would create a pretty impressive reaction as Mg reacts with steam and the burning magnesium would create a lot of steam which would create a good deal of H2.

 

Maybe my ribbon sucks, but when i threw mag ribbon ino water to see a cool reaction, it was extinguished. Got it from united nuclear.. yeah

[woelen]

I also tried this. It simply quenches, no spectacular reaction at all. It is not that the ribbon sucks, but the piece of metal, relative to the amount of water is too small. It probably would work if you had a larger lump of very hot and burning magnesium and put that in a thin layer of water, such that it cannot be totally covered with water.

[warut]

Soon after I read about spectacular reaction between burning Mg and hot water somewhere in this forum, I threw pieces after pieces of burning Mg ribbon in very hot water. Every time the result was the same; Mg fire went out immediately. So I'd very much like to see a video of a successful experiment.

[jdurg]

Hmmm. The piece that I used was a fairly sizeable chunk about the size of a mouse pad and about 1/4 of an inch thick. The thing was a ROYAL pain in the but to ignite, but once it got going the thing went pretty intensely. We then chucked it into the shallow end of a lake and the fire kept going and was igniting the hydrogen as it came off.

 

So it does look like you need a large amount of Mg to really get it going. What you may want to try is to get a little misting spray of water and spray that onto the burning Mg. That might produce a bit of a reaction.

[jrayj]

I tried this too and chunked a red hot lump of magnesium into a stock tank. It just sank, maybe it wasn't hot enough or not burning well enough yet.

[YT2095]

red hot is no good, it must be burning (white hot).

[hydraliskdragon]

If you have some HCl, you could create a generous amount of hydrogen gas with Magnesium.

[Imaginer1]

It depends on the amount of Magnesium, and if you found it in it's real state, you're lucky as heck.