Aqueous magnesium chloride is not used to extract magnesium - why?

[Notagoodtime]

DS’s chemistry homework - struggling to find an answer to the above please

What's the context ? Extract magnesium from what ?

I just googled this and Wikipedia has the answer. You have to extract magnesium from anhydrous magnesium chloride because if you do it in aqueous solution, the magnesium will immediately react with the water.

Does aqueous mean dissolved in water?
Googling suggests you would heat until molten and then use electrolysis

🤦‍♀️

Also, from what is it being extracted? Is it something to do with needing something higher or lower in the reactivity table to displace the magnesium? This is what I vaguely remember from gcse chemistry. But could be totally wrong.

Magnesium is more reactive than hydrogen. If the magnesium chloride is dissolved in water (aqueous), the hydrogen ions in the water will pick up electrons rather than the magnesium. This may help: www.bbc.co.uk/bitesize/guides/zcsyw6f/revision/2 or read a GCSE chemistry section on electrolysis.

Shore break is right. Electrolysis of solution is different to electrolysis of a molten compound, and we rely on the reactivity compared to hydrogen to determine whether magnesium ions or hydrogen ions (both positive ions) can be collected at the negative electrode (where those electrons are) and then become Mg or H atoms

I feel some crap haiku coming on:

I used to know this
Now "atrophy of disuse"
Is all that is left