This is a tool that calculates the change in pressure or absolute temperature of a fixed mass of gas, if the volume is constant, using Gay Lussac's Law.

The tool is multi-directional and, therefore, determines which temperature or pressure needs to be calculated based on which data has been entered. The most typical scenario is to enter an initial pressure and temperature and either the final pressure or temperature, and calculate the other one. However, it is also possible to calculate either the initial pressure or temperature from the entered final values. After one of the pressure or temperature fields has been calculated, further data changes result in the re-calculation of the same field unless that field is itself changed or a different pressure or temperature is cleared.

In more detail, the information that can be entered and/or calculated is:

• The initial pressure of the gas. This does not need to be in any specific unit but should be the same as the final pressure unit, if entered.
• The initial absolute temperature of the gas, in kelvin.
• The final pressure of the gas. This does not need to be in any specific unit but should be the same as the initial pressure unit, if entered.
• The final absolute temperature of the gas, in kelvin.

Associated tool link: http://www.coggit.com/tools/gay_lussacs_law_calculator.html