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Gay Lussac's Law Formula

Gay-Lassac's Law states that at constant volume the pressure of a gas is proportional to its absolute temperature specified in kelvins. For example, if you double the temperature of a gas, we double its pressure and vice versa.

Gay Lussac's Law Formula can be expressed as

The mathematical expression at constant volume and fixed number of moles is given by


Plot of P Vs T at constant volume is a straight line passing through origin. Such a plot is known as isochores.

Gay Lussac's Law Formula of pressure and temperature is equal to

Related Calculators
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Gay-Lussacs Law Problems

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Solved problems based on Gay-lussac's law are given below.

Solved Examples

Question 1: The pressure of a container of helium is 650 torr. If the sealed container is cooled to 0oC, what will the pressure be?
Solution:
 
Since the container is sealed, the volume does not change. Remember that temperature must be in kelvins.

P1 = 650 torr; T1 = 25oC = 298K; T2 = 0oC = 273K

Solving for P2
Since the problem is concerned only with temperature and pressure.
Gay-Lussac's law can be used
 
P2 = $\frac{[650\ torr][273K]}{298K}$ = 595 torr
 

Question 2: If we have a tank of gas at 1.520 torr pressure and a temperature of 300K and it is heated to 500K. What is the new pressure in atmospheres?
Solution:
 
Convert the initial pressure to atmospheres.

$\frac{1520\ torr}{1}$ $\times$ $\frac{1\ atm}{760\ torr}$ = 2.00atm

Solve for P2 in Gay-Lussac's law

P2 = $\frac{P_{1}T_{2}}{T_{1}}$

Substitute the values

P2 = $\frac{[2.00\ atm][500K]}{300K}$ = 3.33atm.
 

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