What's the difference between 解凍（する） and 溶ける


I was studying some new words when I encountered 解凍 which can mean "melt".
This reminded me of 溶ける. How do these words differ? In the case of ice
melting, both can be used right? How about chocolate melting in one's mouth? I
know 溶ける works, but can 解凍する？




解凍する is used for defrosting or thawing whereas 溶ける is used for melting.

解凍する is usually used with the meaning of reversing the action of freezing
something (凍らせる or 冷凍する) — for example defrosting frozen meat — and the result
is that the frozen object returned to its "natural state".

On the other hand 溶ける means something has changed from solid to liquid. When
describing for example molten ice cream you would use 溶ける over 解凍する (the
"natural state" of ice cream is frozen). When defrosting soup, you would you
use 解凍する (the "natural state" of soup is liquid / unfrozen).

So, 解凍する cannot be used to describe melting chocolate in your mouth (the
chocolate was solid, but not frozen). In case of ice/water, you would probably
say 氷が溶けた or 氷を溶かす (ice changing from its "natural state" to water), but if
you're describing for example thawing the frozen water in the water pipe to
your garden shed, you would use 解凍する (reversing the freezing).

