is there an easy way to extract Mg from Mg(OH)2

Simply and concisely, my response to your question is no. Reacting acids with it, shall only produce another salt, and its reactivity makes it difficult to displace. Decomposition of the compound can be induced at relatively low temperatures, around 180 degrees celsius, however this leads to the formation of water, and magnesium oxide. This magnesium oxide then requires incredibly high amounts of heat to allow for the decomposition of the compound. Seriously speaking, I think that it would be a lot easier to simply purchase magnesium, as it is quite a useful chemical to have on hand. Due to its light weight, it used in a variety of lightweight applications, such as alloyed in aircraft parts, and the bodies of pencil sharpeners. The latter, that I have mentioned, is actually quite an easy method, as you can tell that the metal used is magnesium based on its weight. Its best that the blade and screw are removed though, as these are commonly made of steel. Best of luck,

 

,Theophrastus

 

ps: what do you need the magnesium for. If it is a particular application, a substitute can be used.

yeah i react it with water and want to know see if there is a way i can save money by heating or electrolysis to get it back to the usable mg.

no. It won't work.

 

magnesium is cheap and plentiful anyway. why bother? get a metal pencil sharpener or buy some magnesium ribbon.

Agreed, and I find the ribbon is particularly fun, as you can also use it as a fuse for certain exothermic reactions, or coerce a reaction between the magnesium and another substance, by burning it under it. For example magnesium in water makes magnesium hydroxide, and magnesium in sand, can be used to harvest silicon. (Albeit the sample will be full of impurities.) It's also recommended that for safety reasons, you stay clear of the magnesium fumes. Good ventillation, would suffice, however a fume hood is preferable. Cheers!

so you guys are saying that its tottaly impossible to get MgO back to Mg there is no way to ever remove the O?

there are ways but they aren't simple or cheap or safe.

so you guys are saying that its tottaly impossible to get MgO back to Mg there is no way to ever remove the O?

 

Oh it's real simple. Just heat the MgO with molten sodium, potassium, or lithium under argon.