The average kinetic energy of a gas particle depends solely on the temperature of the gas.
Understanding the Relationship
According to the kinetic molecular theory, specifically its last postulate, the average kinetic energy of gas particles is directly proportional to the absolute temperature of the gas. This means:
- Increased Temperature = Increased Kinetic Energy: As the temperature of a gas increases, the average kinetic energy of its particles also increases. This is because the particles move faster and more vigorously at higher temperatures.
- Decreased Temperature = Decreased Kinetic Energy: Conversely, if the temperature decreases, the average kinetic energy of the particles diminishes, leading to slower particle motion.
How Temperature Affects Kinetic Energy
| Temperature Change | Average Kinetic Energy | Particle Motion |
|---|---|---|
| Increase | Increase | Faster |
| Decrease | Decrease | Slower |
Practical Insights
- Heating a Gas: When you heat a gas, the thermal energy supplied is converted into the kinetic energy of the gas particles. They move faster, collide more frequently and with greater force.
- Cooling a Gas: Conversely, cooling a gas reduces the kinetic energy of its particles, slowing down their motion.
Examples
- Hot Air Balloons: The air inside a hot air balloon is heated, increasing the kinetic energy of the air molecules. These energetic molecules move faster, expand and make the air less dense than the surrounding cooler air, allowing the balloon to rise.
- Refrigerator: The cooling process in a refrigerator slows down the movement of molecules in the food items, helping to preserve them by reducing the rate of chemical reactions.
