Boyle’s Law


Boyle’s law also called Mariotte’s law (in French), or Boyle–Mariotte law, refers to an experimental gas law which explains how the pressure of the gas increases as the container’s volume increases. So, Boyle’s law in the modern statement refers to:

The sheer pressure applied by a given mass in a closed system is inversely proportional to the occupied volume if the amount of gas and temperature remains constant.

The law can also be represented as when the temperature is constant, the volume and pressure of a closed system:

V ∝ 1/P which means that Volume is inversely proportional to the Pressure.

P ∝ 1/V which means Pressure is inversely proportional to the Volume.

There are a few methods to express the law in the form of an equation. The very fundamental is:

PV = k, or

P1 X V1 = P2 X V2

The finest way to explain Boyle’s Law is as below:


  • P represents the pressure of the gas
  • V represents the volume of gas
  • K is constant

Characteristics of Boyle’s Law

Boyle’s law is described as that at a constant T, the V of dry gas’ given mass is inversely proportional to its P.


Boyle’s law example

Considering the no. of moles and temperature of the gas remains unchanged, the meaning of Boyle’s law is to double the pressure of a gas and half its volume.

Examples of Boyle’s law:

  1. When the plunger of the sealed syringe is pushed, the pressure accelerates and at that time, volume decreases. Since the boiling point depends upon pressure, Boyle’s law comes in action and a syringe making the water boiling at room temperature.
  2. The fishes found in the deep, die when they are brought to the surface from the depths. The pressure rapidly decreases as they raise-up, and thus, the volume of gases increases in their swim bladder and blood and basically the fish pop.
  3. The same law applies for divers also when they pick-up “the bends”. If the scuba diver or any other diver quickly comes back to the surface, those dissolved gases present in blood swell and expand, and thus form bubbles, and these bubbles can get stuck in organs and capillaries.
  4. If water bubbles are blown underwater, they’ll expand as they rise up to the surface. One concept about how and why the cruises and ships dissipate or just disappear in Bermuda Triangle which has a connection with Boyle’s law. Gases which are released from sea surface rise and widen-up so much that they really convert into a mammoth bubble during the time, they reach to the surface.
  5. In the case of the Bermuda triangle, small boats get drowned in the “hole” and are immersed in the sea.


Simple exercise of Boyle’s Law

A balloon is having 2.0 volume with 3 atmospheres gas filled in it. If its pressure is dropped down to 0.5 atmospheres without temperature change, what would be balloon’s volume?


Since the temperature is fixed change, Boyle’s law has its role Boyle’s gas law is represented as:

P1V1 = P2V2


P1 = initial pressure

V1= initial volume

P2= final pressure

V2 = final volume


V1 = 2.0 L

P1 = 3 atm

P2 = 0.5 atm

Now, V2 = P1V1/P2

= 3 × 2.0/0.5

= 6L/0.5 atm

= 12 L

Finally, the volume of the balloon will be expanded to 12 L.


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