A warm coke bottle fizzes when opened a chemical change?

No, the fizzing of a warm Coke bottle when opened is not a chemical change; it is a physical change. The fizzing occurs because the carbon dioxide gas dissolved in the liquid is released when pressure is reduced upon opening the bottle. This reaction involves the gas escaping from the liquid rather than altering the chemical composition of the substances involved. Thus, while the reaction is a result of a change in state (from dissolved to gas), it does not involve a chemical transformation.