Gay-Lussac’s Law

Gay-Lussac's Law

Gay-Lussac's Law which is most often referred to as the Pressure law, was founded by a French Chemist & Professor Joseph Louis Gay-Lussac in 1809.

Gay-Lussac's Law has also been referred to as Charle's Law, but they are not the same.

Gay- Lussacs Law gives the relationship between pressure and temperature when volume and amount are held constant.

Gay-Lussac found that for a gas, if the pressure increases, the temperature increases, and if the temperature decreases, the pressure decreases. Based on this Gay-Lussac stated his law as " The Pressure of a fixed amount of Gas at a fixed Volume is DIRECTLY proportional to its Temperature ".

Mathematically the Law can be stated as :-

P α T or P = k T or P/T = k

Where,

P is the pressure of the gas in atmospheres,

T is the temperature of the gas in Kelvin &

k is a constant .

Consider,

If P₁ and T₁ is the initial pressure and temperature of a gas,

Then according to Gay-Lussac's Law :

P₁ / T₁ = constant

After the change in pressure and temperature,

P₂ / T₂ = constant

Combining the two equations we get :

P₁ / T₁ = P₂ / T₂

This law holds true because Temperature is a measure of the Average Kinetic Energy of a substance and as the Kinetic Energy of a Gas increases, it's particles collides with the walls of the container more rapidly, thereby exerting an increased Pressure.

Thus from the Gay-Lussac’s law we can say that it may be dangerous to heat a gas in a closed container because the increased pressure might cause the container to explode.