What is Boyle’s Law, Formula,Definition & Examples

What is Boyle’s Law? May be a vital gas law in chemistry. Boyle’s law or the Boyle-Mariotte law is another name of Boyle’s law. The law correlates how the pressure of a gas increases with a decrease within the volume of the gas. During this article, we’ll study Boyle’s law formula thoroughly with its applications and various properties.


Boyle’s law states for a hard and fast amount of an indoor perfect gas, its absolute pressure is inversely proportional to its volume at a continuing temperature. By pertaining to the above figure, Boyle’s law experiment is often understood. The shorter end of the J-shaped tube was closed or sealed while the opposite end was opened to the atmosphere. On the opened end of the tube, Boyle poured mercury. This causes the compression of the air on the closed end of the tube. The compression of the air is thanks to the force exerted by a load of mercury.

same procedure was repeated for various amounts of mercury within the tube and corresponding volumes (the volume of the compressed gas within the shorter end in arbitrary units) and pressures (the height difference of mercury between the 2 ends of the tube) were recorded. From the experiment, Boyle concluded that the pressure of a gas is inversely proportional to its volume.


Boyle’s Law Formula is as follows: 

PV = k

  • where P is pressure
  • V is volume
  • k may be a constant.

The law can also be used to find the pressure or volume of a system when the temperature is held constant:


  • Where P1= First Pressure
  • P2= Second Pressure
  • V1= First Volume
  • V2= Second Volume

From the above expression, it’s clear that the merchandise of the pressure and therefore the volume of a perfect gas is constant at a continuing temperature. When the pressure of a gas at a continuing temperature is double, the quantity reduces to half the initial volume.




Limitation of Boyle’s Law

Boyle’s law is applicable only to ideal gases. The law holds good only at high temperatures and low pressures. The law fails at high pressures. the merchandise of the pressure and volume doesn’t remain constant at high pressures but shows a small increase. This increase is thanks to a rise within the volume which is caused by repulsive forces among the molecules.

The law also can be derived theoretically supported the presumed existence of atoms and molecules and assumptions about motion and perfectly elastic collisions.

Examples for Boyle’s Law Formula

Q1] A gas occupies 12.3 litres at a pressure of 40.0 mmHg. What’s the quantity when the pressure is increased to 60.0 mmHg?

Soln – Given: Pressure P1=40.0 mmHg , Pressure P2=60.0 mmHg , V1=12.3 litres

To find; Volume V2

We have,


(40.0 mmHg) (12.3 litres) = (60.0 mmHg) (x)

x = 8.20 L

So, the quantity when the pressure increases to 60.0 mmHg is going to be 8.2 litres

Q2] 352 mL of chlorine under a pressure of 680 mm, hg are placed during a container under a pressure of 1210 torr. The temperature remains constant at 296 K. What’s the quantity of the container in litres?

Soln – Given ; P1 = 680mm P2 = 1210mm V1 = 352mL

To find; V2 =?

We have,

P1V1 = P2V2

V2 = P1V1/P2V2

= 680. mm x 352 mL/1210 mm

= 198 mL Cl2

Therefore, the quantity of the container in litres is going to be 0.198 litres.

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