Explain why a balloon expands when heated and contracts when cooled.
When a balloon is heated, it expands because the air molecules inside it gain energy and move faster. This increased movement causes the molecules to collide with each other and with the inner walls of the balloon more frequently, creating higher pressure inside. As a result, the balloon stretches and expands to accommodate the increased pressure.
Conversely, when a balloon is cooled, the air molecules lose energy and slow down. This reduction in movement results in fewer collisions and lower pressure inside the balloon. With lower pressure, the balloon contracts, returning to its original size.
To further understand this concept, you can perform a simple experiment. Take an uninflated balloon and place it near a source of heat, such as a flame or a hairdryer, while observing it closely. As the heat is applied, the balloon will gradually expand. Alternatively, you can place the expanded balloon in a cooler environment or expose it to cold air. As the temperature decreases, the balloon will contract back to its original size. These observations confirm the relationship between temperature and the expansion/contraction of a balloon.