What is a Physical Change?
In a physical change, the internal make-up of the object (molecules) stays the same, even after the change — only its form changes. The resulting element can be reversed into the object before. Changes that can be reversed are called Reversible Change.
In a physical change, the state, shape, or size of the object is changed. Pressure, temperature, or motion can bring about a physical change.
Change in state: Put some water into a plastic cup and place it in the freezer. After some time the water changes into ice, right?
The water moved from a liquid state to a solid state. With a bit of heat energy, the ice will melt back into the water. Note that the stuff that water is made up of, hydrogen and oxygen, did not change, but its state changed from liquid to ice and back to liquid.
Change in shape: Take a sheet of paper and crush it in your hands. Notice how the shape changed from a sheet into a small ball in your hands? This physical change resulted from the pressure you applied to it.
Change in size: If the piece of paper is ripped apart, there is going to be a change in its size too.
Sometimes physical change can involve a color change too, even though we don’t like to use color change in explaining a physical change. This is because applying paint or color to an object technically means adding another matter to it. A real color change will be a result of a chemical change.
In a physical change, no new kinds of particles are produced even though the particles can move closer together or farther apart, or they may mix with particles of other substances.
DID YOU KNOW…
When you put sugar in water, it dissolves. It is a physical change because the sugar particles mix with the water particles, but molecule make-up does not change. The process can be reversed by evaporating the water and collecting the sugar.