Enter any 3 values of the initial and final temperatures and pressures of an ideal gas to calculate the missing value using Gay-Lussac’s Law.

Gay-Lussac’s Law Formula

The following formula describes the relations between temperature and pressure in an ideal gas.

P1 / T1 = P2 / T2 
  • Where P1 is the initial pressure
  • T1 is the initial temperature
  • P2 is the final pressure
  • T2 is the final tempature

Guy-Lussac’s Law Definition

Guy-Lussac’s Law states that the pressure of a gas is directly proportional to its temperature, assuming a constant volume and amount of gas.

This law is important because it helps us understand the relationship between pressure and temperature in a gas, allowing us to make predictions and calculations in various scientific and practical applications, such as in the design of engines, weather forecasting, and gas storage.

Guy-Lussac’s Law Example

Let’s look at an example of how to calculate one of the missing values using Gay-Lussac’s Law. Let’s assume we know the initial temperature (5K), final pressure (5Pa), and final temperature (10K). To calculate the initial pressure we must rearrange the equation above to solve for P1. So, P1 = (P2/T2) * T1 = 5/5 * 10 = 10 Pa.


What is Guy-Lussac’s Law?

This law states that in an ideal gas the temperature and pressure are directly proportional. If the pressure goes up by 2 times, the temperature will go up by 2 times.

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gay lussacs law formula