The Formula For Gay-Lussac’s Law

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Gay-Lussac’s Law is a special case of the ideal gas law. This law only applies to ideal gases held at a constant volume allowing only the pressure and temperature to change.

Gay-Lussac’s Law is expressed as:
Pi/Ti = Pf/Tf
where
Pi = initial pressure
Ti = initial absolute temperature
Pf = final pressure
Tf = final absolute temperature

It is extremely important to remember the temperatures are absolute temperatures measured in Kelvin, NOT °C or °F.