Comment by pfdietz
2 days ago
> a small strip of magnesium explodes when dropped in water
No it doesn't.
Magnesium metal burns because the boiling point of magnesium is just 1091 C, so extremely reactive vapor is readily produced. But it would be very hard to heat it that high in water unless it was ignited first. It will then continue to burn under water.
Maybe I should have clarified burning, as in “Why does burning magnesium explode when sprinkled with water?”
https://physics.stackexchange.com/questions/33167/why-does-b...
Yes, safety is a significant disadvantage of the use of magnesium as portable stored energy, but if your ship's payload is already on fire, in most cases the shipment will not be very successful anyway, and loss of the ship is a serious possibility.
If a hypothetical ship full of magnesium sinks without catching the magnesium on fire first, the magnesium will probably not catch fire from exposure to water. Perhaps if it's sufficiently finely divided, which seems like a bad idea.
I agree, the point is you’re not risking something like:
https://en.wikipedia.org/wiki/Halifax_Explosion “At least 1,782 people, largely in Halifax and Dartmouth, were killed by the blast, debris, fires, or collapsed buildings, and an estimated 9,000 others were injured.”
“Nearly all structures within an 800-metre (half-mile) radius, including the community of Richmond, were obliterated.[3] A pressure wave snapped trees, bent iron rails, demolished buildings, grounded vessels (including Imo, which was washed ashore by the ensuing tsunami), and scattered fragments of Mont-Blanc for kilometres. Across the harbour, in Dartmouth, there was also widespread damage.[4] A tsunami created by the blast wiped out a community of Mi'kmaq who had lived in the Tufts Cove area for generations.”
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