Question

Why does your tongue feel cold when you put some glucose on it?

Answer 1

We feel cool when glucose is kept on our tongue because it absorb latent heat of vapourisation from our body.

Answer 2

When glucose powder is eaten our touched to our tongue, our tongue feels because it absorbs the latent heat of vaporization from body and makes it cold in return.

The process takes energy from its surrounding and takes all the heat energy therefore, it can be called as endothermic reaction