

How Does Boyle’s Law Describe Gas Pressure and Volume?
When it comes to preparing for exams like JEE, it is really crucial to make sure that there is strong clarity when it comes to areas like laws and principles. There are many such laws and principles that students have to learn in order to score their best in these exams. However, it is not very difficult to understand these laws as well. One such law that we will be talking about is Boyle's Law. Boyle's law is a very important part of your syllabus as it has a large number of problems based on it. It is one of the most crucial parts of chemistry that you will study in your journey as a student.
This article will be based upon the same. The aim of the article is to break every single tiny detail down about what Boyle's law is and what its details are. Details about the application of the law, the history of the law, all the way to solving problems based on the law. We recommend that students use this document a lot to make sure that they are not losing any of this valuable content from the article.
Vedantu intends to clarify everything about this law through this article and plans to make sure that by the end of this article, you are left with a lot of knowledge regarding the topic and have a good hold on the topic.
With that being said, we recommend that students take notes while using this document and use it to solve as many problems based on the law as possible.
Boyle’s law is an experimental gas law. The relationship between pressure and volume of a gas was 1st noted by Richard Towneley and Henry Power. Then Robert Boyle an Anglo-Irish natural philosopher, chemist, physicist, and inventor confirmed their discovery through experiments and published the results in 1662. This is the reason it is named after Robert Boyle and known as Boyle’s law. The law is also referred to as Boyle – Mariette law or Boyle-Mariette's law as the French physicist Edme Mariotte also discovered the same law independently of Boyle in 1679.
Boyle’s law describes how the volume of a gas changes with a change in pressure when the temperature and mass of the gas are kept constant.
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What is Boyle’s Law?
Boyle’s law states that “the absolute pressure exerted by a given mass of an ideal gas is inversely proportional to the volume it occupies if temperature and amount of gas remain unchanged within a closed system.”
Mathematical expression of Boyle’s law –
P ∝ 1/V--------(1)
Where P is the pressure of the gas and V is the volume of the gas.
It means that for gas if the temperature is maintained constant and a number of moles or amount of gas is also kept constant then on increasing the pressure, the volume of the gas will decrease. While decreasing the pressure, the volume of the gas will increase.
On removing the proportionality from equation (1) –
PV = k
Where k is the constant.
Thus, Boyle’s law can also be usefully expressed as –
\[P_{1}V_{1} = P_{2}V_{2} = P_{3}V_{3} = …..= k (Constant)\]
Graphical Representation of Boyle’s Law
At constant temperature for a given mass (constant mass) of a gas, if we draw a graph of pressure against volume then we get the following graph –
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At constant temperature for a given mass (constant mass) of a gas, if we draw a graph of volume against pressure then we get the same graph as above –
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At constant temperature for a given mass (constant mass) of a gas, if we draw a graph of pressure against 1/V then we get the following graph –
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At constant temperature for a given mass (constant mass) of a gas, if we draw a graph of volume against 1/P then we get the following graph –
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All the graphs above support the statement of Boyle’s Law.
Applications of Boyle’s Law
Applications of Boyle’s law can be seen in our everyday life. Even the human breathing system is an example of the application of Boyle’s law. Few of its real-life applications have been listed below –
Working of Syringe- The working principle of the syringe is based on Boyle’s law. When we pull the plunger of the syringe it increases the volume inside the barrel which causes lower pressure inside it and it results in the external fluid coming inside the barrel.
Human Breathing- As the lungs expand, the volume of the lungs increases so pressure decreases (Boyle’s Law). Now as the pressure is lower inside the body than the outside, air comes into the lungs from outside. Thus, the inhalation process takes place. While during exhalation, the volume of the lungs decreases, and pressure increases so air goes out.
Bicycle Pump- The working of bicycle pumps is also based on Boyle’s law. It works the same as a syringe.
Boyle’s law is also used in space by astronauts, scuba drivers, etc.
This was brief on Boyle’s Law, if you are looking for detailed study notes on various related topics of chemistry then log on to the Vedantu website or download the Vedantu learning app. By doing so, you will get access to NCERT Solutions, study notes, revision notes, mock tests, and much more.
Conclusion
Boyle's law is a very important part of chemistry. This article focused on the detailed analysis of what exactly the law is about and how it functions. The article also highlighted some key points that you need to remember that showcase the application of Boyle's Law. One of the most important things that you will see whenever someone discusses Boyle's law is its graphical representation. The graphical representation of Boyle's law is not a very complex thing to understand, however, we do suggest that students reread that specific part of the article more to avoid any kind of confusion.
We hope that through this article the idea behind Boyle's law was clarified fully and that you were able to draw inferences from the various applications that we had mentioned in this article. Vedantu appreciates its students for the constant support that they give us and hopes that this article helps you in clearing all your doubts regarding Boyle's law.
If you have any doubt or queries then feel free to drop a comment below so that other members of the Vedantu community can help you out!
FAQs on Boyle’s Law: Principles, Formula, & Real-Life Uses
1. What is the fundamental principle of Boyle's Law?
Boyle's Law states that for a fixed mass of an ideal gas kept at a constant temperature, the pressure is inversely proportional to the volume. This means that if you increase the pressure on the gas, its volume will decrease proportionally, and vice versa. The product of pressure and volume remains constant.
2. What is the mathematical formula used to represent Boyle's Law?
The relationship in Boyle's Law is expressed by the formula P₁V₁ = P₂V₂. Here:
- P₁ is the initial pressure of the gas.
- V₁ is the initial volume of the gas.
- P₂ is the final pressure of the gas.
- V₂ is the final volume of the gas.
3. What are some real-life examples that demonstrate Boyle's Law?
Boyle's Law can be observed in many everyday situations. Key examples include:
- Human Breathing: When we inhale, our diaphragm increases the volume of our lungs, which decreases the pressure inside, causing air to rush in. The opposite happens when we exhale.
- A Syringe: Pulling the plunger back increases the volume inside the syringe, which reduces the pressure, drawing liquid in. Pushing the plunger decreases the volume, increasing the pressure and forcing the liquid out.
- Scuba Diving: As a diver descends, the external water pressure increases, causing the volume of air in their lungs and gear to compress. They must exhale during ascent to release this expanding air safely.
- Aerosol Spray Cans: The contents are stored under high pressure. Pressing the nozzle opens a valve, and the high-pressure gas expands into the low-pressure atmosphere, pushing the liquid out as a spray.
4. How is Boyle's Law represented graphically?
The graphical representation of Boyle's Law shows the inverse relationship between pressure (P) and volume (V). When plotting Pressure vs. Volume, the graph is a rectangular hyperbola. This curve is called an isotherm because it represents the changes at a constant temperature. However, if you plot Pressure vs. the inverse of Volume (1/V), the graph is a straight line passing through the origin, which clearly illustrates their direct proportionality (P ∝ 1/V).
5. What are the essential conditions under which Boyle's Law is valid?
Boyle's Law is not universally applicable and holds true only under specific conditions. The two most important conditions are:
- Constant Temperature: The temperature of the gas must remain unchanged throughout the process. Any change in temperature would affect the kinetic energy of gas particles and thus alter the pressure-volume relationship.
- Fixed Amount of Gas: The mass, or number of moles, of the gas must be constant. If gas is added or removed, the relationship described by P₁V₁ = P₂V₂ will no longer be valid.
6. Why is the concept of Boyle's Law significant in understanding gas behaviour?
Boyle's Law is significant because it was one of the first quantitative laws to describe the behaviour of gases. It establishes a predictable, inverse relationship between pressure and volume, which is a cornerstone of the kinetic theory of gases. This principle helps explain why compressing a gas increases its pressure and provides a foundational model for the development of more complex gas laws, such as the Ideal Gas Law (PV = nRT).
7. How does Boyle's Law differ from Charles's Law?
The primary difference lies in the variables they relate and the conditions they hold constant. Boyle's Law describes the relationship between pressure and volume (P-V) while keeping the temperature (T) constant. In contrast, Charles's Law describes the relationship between volume and temperature (V-T) while keeping the pressure (P) constant. Both laws assume a fixed mass of gas.
8. Why does the P vs. 1/V graph for Boyle's Law produce a straight line?
The reason for the straight-line graph lies in the mathematical rearrangement of Boyle's Law. The law states that P ∝ 1/V, or P = k(1/V), where 'k' is the constant of proportionality. This equation is in the form of the general equation for a straight line, y = mx + c. In this case, y corresponds to Pressure (P), x corresponds to the inverse of Volume (1/V), the slope 'm' corresponds to the constant 'k', and the y-intercept 'c' is zero. Therefore, plotting P on the y-axis and 1/V on the x-axis results in a straight line passing through the origin.

















