See what happens when you put your hand in hot ice
If you’ve ever marveled at the wonder of hand warmers – those hard flat packs that heat up when you bend them – then this video will amaze you.
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A scientist from the University of Toronto, Canada, is filmed putting his hand in a jar of hot ice, or molten sodium acetate, so it crystallizes around his fingers.
In a matter of seconds, the man’s fingers are coated in a thick layer of ice. But instead of being cold, the scientist explains that his hand is actually quite warm, ‘like a hot bath’.
In this video I stick my hand into a jar full of molten sodium acetate and have it crystallize with my hand inside.
This works because the substance is not “ice” as in water, but a different substance called sodium acetate trihydrate. Normally solid sodium acetate was melted into a liquid that was then supercooled to below its melting point. In this state, adding nucleation sites, like the crystals on my hand, rapidly causes the rest of the sodium acetate to crystallize.
WHAT IS HOT ICE?
‘Hot ice’ is created using sodium acetate, which is a salt created from the reaction between sodium bicarbonate, or baking soda, and acetic acid, or vinegar.
When this reaction occurs, sodium acetate appears to freeze like ‘ice’ as the cold solution turns from liquid to solid.
This process is exothermic, meaning that the solid structure is warm to the touch.
Solutions of sodium acetate are used in certain types of hand-warmers.
When a metal button is pressed inside the plastic pouch containing the solution, it releases chemicals that starts the reaction.
This causes the solution to crystallize, and this reaction generates heat.
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