Boyle’s Law: Definition, Applications, Limitations And Examples!

Boyle’s Law; Definition, Applications, Limitations And Examples: Boyle’s Law formulated by Robert Boyle in 1662, states that for a fixed amount of gas at a constant temperature, the pressure and volume are inversely proportional. 

For example, if you squeeze a gas, the pressure it exerts will increase and vice versa. 

Boyle’s Law Formula

For a gas, the relationship between volume and pressure can be expressed mathematically as follows: 

P ∝ (1/V)

p pressure exerted by the gas

v= volume occupied

This can be converted into an equation by adding a constant, K. 

P = k*(1/V) ⇒ PV = k

The pressure v/s volume curve for a fixed amount of gas kept at constant pressure is illustrated below:-

It can be observed that a straight line is obtained when the pressure exerted by the gas P is taken on the Y-axis and the inverse of the volume that is occupied by the gas is taken on the Y-axis. 

Formula And Derivation

As per Boyle’s law, if there is any change in the volume occupied by gas, then it will result in a change in pressure exerted by it. The product of the initial pressure and the initial volume of the gas is equal to the product of its final pressure and volume. 

Mathematically, the equation can be expressed as follows:- 

P1V1 = P2V2

P1- initial pressure exerted by the gas 

V1- the initial volume occupied by the gas 

P2- final pressure exerted by the gas

V2-  final volume exerted by the gas

For a fixed amount kept at a constant temperature, PV=k, so, 

P1V1 = k 

P2V2 = k 

Therefore, P1V1 = P2V2

This equation can be used to predict the increase in the pressure exerted by the gas on the walls of its container when the volume of its container is decreased. 

Visualising Boyle's Law

• Think of gas as a collection of tiny particles constantly bouncing around. If you compress the gas, this means that you can cram these particles into smaller spaces. 
• This increases the frequency of collisions between the particles and the container walls, which in turn leads to higher pressure. 
• Expanding the volume allows the particles to give more space so that they can reduce the collisions and reduce the pressure. 

Applications of Boyle's Law

There are various applications based on Boyle’s Law:- 

• Understanding respiration: The decrease in pressure when you inhale and your diaphragm contracts, increasing the lung volume is the application of Boyle’s law that allows the air to rush into your lungs. 
• Scuba Diving: As a scuba diver descends deeper, the pressure around them increases. So, this is also an application of Boyle’s law. 
• Manufacturing: Boyle’s law can help engineers design the equipment and handle the pressure changes associated with gas compression. 

Limitations Of Boyle’s Law

• Boyle’s law is an ideal gas law and it assumes perfect gas behaviour, which isn’t always the case with real gases, especially at extreme pressures and temperatures. 
• At extremely low pressures, the volume of even ideal gas would start to decrease more rapidly than predicted by Boyle’s law. 

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