What type of change is occurring when a substance transforms from one state of matter toanother?

The type of change that is occurring when a substance transforms from one state of matter to another is called a phase change or a state change. This is a physical change, not a chemical change.

Here are the steps of how it happens:

1. Energy is added or removed: In order for a substance to change states, energy (in the form of heat for example) must be either added or removed.

2. Change in kinetic energy: When energy is added, the kinetic energy of the substance's particles increases. They move faster and the substance heats up. When energy is removed, the kinetic energy decreases, the particles move slower and the substance cools down.

3. Change in state: If enough energy is added or removed, the substance will change states. For example, adding energy to a solid will turn it into a liquid (melting), and adding more energy will turn it into a gas (evaporation). Conversely, removing energy from a gas will turn it into a liquid (condensation), and removing more energy will turn it into a solid (freezing).

4. No change in chemical composition: Throughout this process, the chemical composition of the substance does not change. Only the state of the substance changes.

So, the transformation from one state of matter to another is a physical change known as a phase change or state change.