Chemical Transformations seen Daily?

Question

What are some chemical transitions that you use daily? Like what is the "chemical" and how do you recognize that a chemical change has taken place?

Answer 1

Driving .. you fill up your car with gas, drive around, then you recognize the change when you have to refuel again

Answer 2

Digestion, what goes in is a lot different than what comes out, and obviously some energy is produced.

Answer 3

Cooking, just try the taste of meat before and after cooking, taste how the proteins have reacted under effet of heat...