The chemicals have to be in contact with each other in order for any type of chemical reaction to take place. One of the most common examples of a chemical reaction is the rusting of a fence. The combining of the metal and the oxygen causes bonds to break and new ones to be created, which results in the creation of iron oxide or rust.
The ear canal cleans itself with a waxy secretion called cerumen. Cerumen is resistant to water, sticky (to trap dust) and migrates out of the ear canal to self-clean the ear. Sometimes, the wax builds up and causes symptoms, including mild deafness and a sensation of fullness inside the ear.
Ear wax is produced by glands in the skin of the outer portion of the ear canal. Sound enters the ear and travels down the ear canal until it reaches the eardrum. The eardrum is approximately 8-10mm in diameter and is formed of three layers of skin. It's a bit like a drum-skin, which vibrates when sound strikes it. When this happens, the sound vibrations are passed into the middle ear.