Why is an endothermic reaction cold?
We would write an endothermic reaction from
Of course the heat has to come from somewhere...and it comes from the surroundings. Have you ever used a cold-pack as a first aid device? These are usually solid mixes of ammonium nitrate (and other salts) with a blister of water... When you use it you BREAK the blister, and the water reacts with the ammonium salt.
And such a reaction can be used to provide topical relief to swelling or a strain...