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Boyle’s Law- Statement, Equation, Representation, Applications, Practice Problems & FAQs
To understand Boyle’s law, let's look at the following setup. What [1] do you think would happen if we press the plunger of the syringe? Yes, you got it correct![2] The volume will decrease but at the same time, the pressure of the air inside the syringe will increase[3] . In the year 1662, Robert Boyle showed the relationship between pressure and volume of gas through different experimental observations and named it Boyle’s law which helps to explain different observations in everyday life.
Table of content
- Statement of Boyle’s law
- Equation of Boyle’s law
- Graphical representation of Boyle’s law
- Applications of Boyle’s law
- Practice problems
- Frequently asked questions-FAQs
Statement of Boyle’s law
According to Boyle’s law “At constant temperature and for a fixed amount of gas, the pressure of the gas varies inversely with the volume of the gas”.
Equation of Boyle’s law
Mathematically it can be represented as;
Constant
Where 
represents pressure exerted by the gas, 
is the volume occupied by the gas and 
represents the constant of proportionality.
Note: The above relation of pressure and volume is shown considering the temperature and amount of gas to be constant.
Mathematical representation of Boyle’s law under two different pressure and volume conditions:
Using Boyle’s law for both Case
and Case
, we get;
From equation 
and 
, we get,
Constant
Where 
represent pressure exerted by the gas and volume occupied by the gas in Case respectively and 
represent the pressure exerted by the gas and volume occupied by the gas in Case respectively.
Graphical representation of Boyle’s law
The 
curve for a fixed amount of gas and at a constant temperature is represented as;
According to the equation;
Pressure exerted by the gas is inversely proportional to the volume occupied by the gas, so if pressure
is taken on the 
-axis and volume 
on the 
-axis, the nature of the curve would be rectangular hyperbola and you can see from the graph that pressure is increasing when the volume is decreased.
Applications of Boyle’s law
- Filling of natural gas in containers
- Working of a cylinder-piston arrangement
- Wearing spacesuit in space
- Ascending gradually during scuba diving
Practice problems
Q1. A 
cylinder with flexible walls containing nitrogen at a pressure of 
is allowed to expand at constant temperature such that the final pressure of the nitrogen becomes
The final volume of the cylinder is: (Assuming nitrogen present in the flask behaves ideally)
Answer: (A)
Solution:
According to the given data,
Initial volume of the cylinder 
Initial pressure of nitrogen gas in the cylinder 
Final pressure of nitrogen gas in the cylinder 
Let the final volume of the cylinder be 
Using Boyle’s law we get,
Putting the values in the above expression we get,
Q2. An ideal gas undergoes compression at a constant temperature, which reduces its volume by
. The final pressure and the volume of a gas are 
and 
respectively. Calculate the original pressure of the gas in 
.
Solution: Let the original pressure be 
.
Initial volume of the gas 
Final volume of the gas 
+ Reduction in volume
Final pressure exerted by the gas 
Using Boyle’s Law and putting the values we get,
Q3. Calculate the percentage change in volume of an ideal gas if it is compressed at 
from
to 
Solution: Let the initial and final volume of an ideal gas be 
and 
respectively.
Initial pressure 
Final pressure 
Using Boyle’s Law and putting the values we get,
⇒ 
% Change in volume = 
100}
Putting value of 
from equation 
100}
Note: 
sign here signifies a decrease in volume of an ideal gas.
Q4. Slope of the plot between 
and 
at constant temperature is_______.
Answer : (A)
Solution:
As shown in the graph above plot is parallel to the 
axis and therefore,
Slope 
Frequently asked questions-FAQs
Q1. How does Boyle's law have practical application in scuba diving?
Answer: We are aware of the fact that according to Boyle's law, pressure and volume are inversely related to each other. So, if a diver takes a lung full of air underwater, that air will expand his lungs as he rises to the surface because the pressure is higher underwater and at the surface, pressure is reduced. If he ascends too rapidly or holds his breath the expanding air can rupture his lungs.
Q2. How density of gas and pressure can be related considering the gas obeying Boyle’s law?
Answer: According to Boyle’s law we know that pressure and volume are inversely related considering temperature and amount of gas to be constant.
, since the amount of gas is assumed to be constant.
Therefore, 
.
According to Boyle’s law,
Pressure of the gas 
So, considering 
, it can be said as;
Density of the gas is directly proportional to the pressure of the gas.
Q3. Why do inflated balloons burst when it is compressed?
Answer: When the inflated balloon is compressed its volume decreases. We know, according to Boyle’s law, pressure is inversely proportional to the volume of the gas. Therefore, on decreasing the volume of the inflated balloon pressure inside the balloon increases and it burst.
Q4. Why are gases highly pressurized while storing them in a small container?
Answer: Gases are generally pressurized when stored in a small container. We know, according to Boyle’s law, pressure is inversely proportional to the volume of the gas. Therefore, pressurizing the gas decreases the volume occupied by the gas and a larger volume can be stored in the small containers.
Related topics
| Charles's Law | Gay-Lussac’s Law |
| Avogadro’s Law | Dalton's Law of Partial Pressure |
| Ideal Gas Equation | Real Gas |
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