Question

What are two ways to tell if a chemical reaction is taking place?

Answer 1

1) temperature change
2)odor or smell change
Hope this helps

Answer 2

A chemical reaction is observed by physical effects that cannot be undone, for Ex. If an object give off heat or light, thats a chemical reaction. If theirs a change in an objects color it can be a chemical reaction, like rust. Metal turning silver to brown.