Final answer:
When a canister of compressed air is emptied, the closely packed molecules spread out to fill the surrounding lower-pressure space, absorbing energy and causing the canister nozzle to feel cold. This process illustrates the different properties of matter in solid, liquid, and gas states, with the gas state being characterized by the freedom of particle movement and energy distribution.
Step-by-step explanation:
During the demonstration of emptying a canister of compressed air, we witness changes at the particle level that involve a redistribution of matter and energy. Initially, the compressed air molecules inside the canister are closely packed together, exerting forces upon one another. As the air is released, these molecules spread into the surrounding room air, which has a lower pressure. This expansion requires energy to overcome the intermolecular forces, leading the nozzle of the canister to feel cold as the molecules absorb energy from the surroundings during their expansion.
Additionally, the three states of matter—solid, liquid, and gas—are characterized by different levels of particle energy and movement. In solids, particles vibrate but do not change position, while in a gas, particles move much more freely due to decreased attractive forces. In the canister demonstration, the gas molecules transition from a highly ordered (compressed) state to a disordered state with increased movement and energy spread as they disperse into the room.