The Ideal Gas Law, represented by the equation PV = nRT, describes the relationship between pressure (P), volume (V), and temperature (T) of an ideal gas. This law is essential for understanding how gases behave under different conditions. Here are three practical examples that illustrate this relationship.
In everyday life, we frequently encounter scenarios involving gases, such as inflating a balloon. When you blow air into a balloon, you’re increasing the volume of gas inside, which affects both the pressure and temperature.
When the balloon is empty, the volume is minimal, and the air pressure inside is equal to the atmospheric pressure outside. As you blow air into the balloon, you’re increasing the number of gas molecules, which raises the pressure inside the balloon. The temperature can also rise slightly due to the work done on the gas as you inflate it. If you were to measure the pressure and volume of the balloon after inflation, you could observe how they relate to the temperature using the Ideal Gas Law.
Consider a syringe filled with gas. If you pull back the plunger, you increase the volume of the gas. According to the Ideal Gas Law, if the temperature remains constant, the pressure inside the syringe will decrease as the volume increases.
Imagine you have a syringe with a volume of 10 mL at a temperature of 25°C (298 K) and a pressure of 2 atm. When you pull back the plunger, increasing the volume to 20 mL, the pressure will drop. If you were to calculate the new pressure using the Ideal Gas Law, you would find that the pressure is now 1 atm if the temperature remains constant. This example helps illustrate the inverse relationship between pressure and volume when temperature is held constant.
Weather balloons are an excellent example of how pressure, volume, and temperature interact in the atmosphere. As a weather balloon ascends, it experiences a decrease in atmospheric pressure. According to the Ideal Gas Law, as the external pressure drops, the volume of the gas inside the balloon expands.
At sea level, a weather balloon might have a volume of 2 m³ and a temperature of 15°C (288 K) with an internal pressure of 1 atm. As it rises, the external pressure decreases, allowing the balloon’s volume to expand significantly, often reaching volumes of 30 m³ or more before bursting at high altitudes. This phenomenon can be modeled using the Ideal Gas Law to predict the behavior of the gas under different temperature and pressure conditions.