Exploring physical and chemical changes
In the following scenarios, tell whether the change being described is a physical or a chemical change, and explain the reasoning behind your answer.
A carbonated beverage container is opened, producing a fizzing sound and carbon dioxide (CO2) bubbles.
Dry ice (solid CO2) is taken from a freezer and placed in an ice bucket at room temperature. With time, the block decreases in size and is surrounded by a visible cloud.
A pastry chef adds a mixture of white vinegar (~5% acetic acid in water) and baking soda (sodium bicarbonate, NaHCO3) to the batter for a red velvet cake to create bubbles that make the cake rise.
A shiny, silvery iron nail turns reddish-brown when left exposed to the weather.
A chemical heat pack is manufactured by sealing water (H2O) and calcium chloride (CaCl2) in separate compartments of a container. When the two components are mixed, the CaCl2 dissolves in the water, producing a large amount of heat.