What is cheotic?

Why does the conversion of chemical energy to thermal energy cause entropy to increase?

a good example of chemical energy is gass, gass is a good fuel because there are alot of bonds in these long chains of carbons. When you convert chemical energy to thermal energy you are basically ripping all of the bond in thoes carbon chains apart which releses energy in the form of heat. and the end result is alot of smaller molicules. so you broke up order and made it more cheotic