1. The problem statement, all variables and given/known data To deaden pain in minor operations, a liquid that vaporises easily is often sprayed on the affected area. How does this prevent the pain being felt? Would water have the same effect? 2. Relevant equations none 3. The attempt at a solution Vaporises easily => absorbs heat quickly and leaves the skin. Does cooler skin at damaged area => less pain felt? How does one feel pain? Does one feel pain by sensory cells firing into the brain via the central nervous system? So a cooler temperature in the affected area => slower firing of these sensory cells? Hence brain registering pain slowly and decreased in magnitude as cool=>low energy on the cells behalf.