Defining the Combined Gas Law
The Combined Gas Law is a fundamental principle in chemistry and physics that integrates three other gas laws: Boyle's Law, Charles's Law, and Gay-Lussac's Law. It describes the relationship between the pressure, volume, and absolute temperature of a fixed amount of gas, stating that the ratio of the product of pressure and volume to the temperature is a constant.
Section 2: The Formula
The mathematical formula for the Combined Gas Law is expressed as (P₁V₁)/T₁ = (P₂V₂)/T₂. In this equation, P₁ and V₁ are the initial pressure and volume, and T₁ is the initial absolute temperature. P₂, V₂, and T₂ represent the final pressure, volume, and absolute temperature, respectively. It is crucial that the temperature (T) is always measured in Kelvin (K).
Section 3: A Practical Example
Imagine a weather balloon with a volume of 100 L on the ground, where the pressure is 1 atm and the temperature is 27°C (300 K). As the balloon rises, the pressure drops to 0.5 atm and the temperature cools to -23°C (250 K). Using the formula, we can find the new volume: V₂ = (P₁V₁T₂)/(T₁P₂) = (1 atm * 100 L * 250 K) / (300 K * 0.5 atm) = 166.7 L. The balloon expands as it rises.
Section 4: Why Is It Important?
The Combined Gas Law is incredibly useful because it allows scientists and engineers to predict how a gas will behave when multiple conditions change simultaneously, as long as the amount of gas remains constant. It has practical applications in fields like meteorology (for weather balloons), scuba diving (to understand how air in tanks behaves at different depths), and engineering.