While preparing for competitive exams like NEET, JEE, etc., it is necessary to have concepts like the laws and principles of Physics and Chemistry as clear as possible. Students must understand various rules and regulations to achieve their best results on these tests. These laws, on the other hand, are not difficult to comprehend. Boyle’s Law in Chemistry is one of the laws we shall discuss in this article. Boyle’s law is an important component of your curriculum because it forms the foundation for many problems. It is one of the most important aspects of Chemistry in 2022 that you will learn as a student.
What is Boyle’s Law?
The fundamentals of this article are to make students crystal clear about Boyle’s Law. This article dissects every last detail of what Boyle’s law is and what it entails. Information on applying the law, the history of the law, and how to solve problems based on the law are all included. We recommend that students utilize this document frequently to ensure that they do not miss any of the article’s important information. Let us begin with the statement of Boyle’s Law:
Boyle’s law says that “the total pressure employed by an ideal gas of given mass ‘m’ is inversely proportional to the volume it occupies. This is applicable when the temperature and amount of gas remain unaffected within a closed system.” We shall break every part of this statement while learning about Boyle’s Law further in the article. But, first, let us know how this law came into existence?
History of Boyle’s Law
Richard Townley and Henry Power initially observed the relationship between the pressure and volume of fluids in the early 17th century. But they couldn’t prove it. Later in 1662, Robert Boyle experimented on their theory and published the outcomes with his name, hence making the law known to be ‘Boyle’s Law’.
Did You Know: Robert Hooke, the assistant, and lab in charge of Boyle, built the entire apparatus for the experiment. This was revealed later by Robert Gunther and other authorities.
Boyle was probably interested in the various ways in which air contributes to living; for example, he wrote on plants’ ability to develop without air. Boyle started to discover this law by experimenting with air, as he always thought air was one element.
In Boyle’s experiment, he poured mercury from one side of the tube. The air on the other side was pressed to compress under the pressure of mercury. Using various levels of mercury and performing the experiment multiple times, he discovered that the pressure of a gas is inversely related to its volume under controlled conditions. Hence giving us the very famous law of ideal gases known as Boyle’s Law.
Interesting fact: Edme Mariotte (1620-1684) in 1679 proved the relationship of pressure and volume of an ideal gas without any help, but Boyle beat him as Boyle’s law had already been published in 1662.
Boyle’s Law Maths
Let us now learn Boyle’s Law mathematically because, in the NEET 2022 examination, you shall find numerical questions related to Boyle’s law. These questions require a lot of understanding, and you must be clear with the derivation of the mathematical formula of Boyle’s Law to solve its problems.
According to the statement of Boyle’s Law
Pressure ∝ 1/Volume
Thus we can write, P ∝ 1/V ———————– eq. 1
P and V are the pressure and volume of gas, respectively.
From this, we can deduce that for gas, if the temperature is kept constant and likewise, the amount of gas is kept constant, the volume of the gas will decrease as the pressure increases.
The reverse is also true if the pressure is decreased, the volume increases.
From equation 1
P ∝ 1/V
PV ∝ 1
Eliminating the proportionality sign we get
PV = 1 x k
‘k’ is a constant value.
This gives us the result as
PaVa = k
PbVb = k
PcVc = k, and so on.
Thus we can say that PaVa = PbVb —————– eq. 2
Here PaVa = the initial pressure x the initial volume of Gas ‘A’, and PbVb = the final pressure x the final volume of gas ‘A’.
Using this equation, anyone can predict the initial volume of a gas if the other three values are known. This equation can help you find out four different physical quantities. In NEET questions, it is seen that 3 out of 4 values are given in the question, and the one unknown value has to be found out. That unknown value is your answer.
Graphical Representation of Boyle’s Law
Graphical representations of Boyle’s Law are the most asked topic in the NEET examination. According to research, one or two questions have been asked from Boyle’s Law graphical representation every year. Look at the graphs below carefully and keep them in your mind as sometimes they are directly asked in the paper.
The graph between pressure and volume: Each isotherm is a rectangular hyperbola that corresponds to a specific fixed temperature. The graph’s higher curves correspond to higher temperatures.
The graph between pressure and inversely proportional to volume: This graph results in straight lines.
The graph between pressure and volume with pressure: As seen in the graph below, the product of the gas volume is always fixed at a certain temperature.
Note: It’s important to remember that the pressure is cut to half.
Boyle’s Law Application
Boyle’s law has numerous applications in our daily lives. From a tiny syringe to the building of space suits, Boyle’s Law is prevalent. Even the human respiratory system is an example of Boyle’s law in action. Below we have listed a few common applications of Boyle’s Law, even previously asked in the NEET examination.
- Syringe and Bicycle Pump Operation- The syringe’s operation is based on Boyle’s law. When we draw the syringe plunger, we increase the volume inside the barrel, which lowers its pressure, allowing external fluid to enter the barrel. Boyle’s law also governs the operation of bicycle pumps. It functions similarly to a syringe.
- Breathing Mechanism: Boyle’s Law states that when the lungs expand, the volume of the lungs increases, and pressure lowers. Because the pressure inside the body is lower than outside, air enters the lungs from the outside. As a result, the inhaling process occurs. Exhalation causes the volume of the lungs to drop and the pressure to rise, causing air to escape.
- Astronauts, scuba divers, and other space travellers use Boyle’s law. The pressure decreases when a scuba diver ascends from the deep ocean to the water surface. This causes the gas molecules in their body to expand. These gas bubbles can harm the diver’s organs and perhaps cause death.
Curiosity Enough: Did you know often fishes die on reaching from the ocean bed to the water surface? Boyle’s Law explains this phenomenon. Similar to what we studied in the case of scuba divers, on reaching the water’s surface, the dissolved gases in the blood of fishes start to expand, causing the death of fish on the water’s surface.
We have provided you with two very good examples of how the numerical questions from Boyle’s law may appear in the NEET 2022 exam. Carefully go through the stepwise solutions of both examples.
Example 1: A unit litres of gas fills a container and exerts a pressure of 200 kPa on its wall. This gas is now transferred to another vessel having a capacity of 4 litres. Find the pressure exerted by the gas in the second container.
Solution: We are given,
Initial volume (Va) = 1 litres
Initial pressure (Pa) = 200 kPa
Final volume (Vb) = 4 litres
We know that according to Boyle’s Law: PaVa = PbVb
Therefore Pb = PaVa / Vb
Pb = ( 1 x 200) / 4
= 50 kPa
Therefore, the gas exerts 50 kPa pressure on the 4 litres container.
Example 2: On the walls of container A, a gas exerts a pressure of 5 kPa. The pressure exerted by the gas grows to 20 kPa when container A is emptied into a 4-litre container. Calculate container A’s volume.
Initial volume (Va) = Not known
Initial pressure (Pa) = 5 kPa
Final pressure (Pb) = 20 kPa
Final volume (Vb) = 4 litres
We know that according to Boyle’s Law: PaVa = PbVb
Therefore Va = PbVb / Pa
Va = ( 20 x 4) / 5
= 16 litres
Therefore, the volume of container A is 16 litres.
Boyle’s law is a fundamental concept for NEET 2022 Chemistry. This article focused on a deep examination of what the law is all about and how it works. The post also highlighted some crucial facts to remember that demonstrate Boyle’s Law’s application. The graphical representation of Boyle’s law is one of the essential things you’ll see whenever it’s discussed. Although the graphic illustration of Boyle’s law is not difficult to grasp, we recommend that students review that section of the text to avoid any misunderstandings.
We hope that by reading this article, you gained a better understanding of Boyle’s law and concluded from the numerous examples we discussed.
Frequently Asked Questions on Boyle’s Law
- What is the statement of Boyle’s law?
Ans. Boyle’s law asserts that pressure and volume are inversely related. When the temperature is constant, pressure rises as volume rises and vice versa.
- State the principle of Boyle’s Law?
Ans. Boyle’s law is significant because it describes the behaviour of gases. It establishes that gas pressure and volume are inversely proportional. The volume of a gas shrinks, and the pressure rises when pressure is applied to it.
- Boyle’s gas law has a formula. What is it?
Ans. As suggested by scientist Robert Boyle in 1662, the empirical relation states that the pressure (P) of a given quantity of gas changes inversely with its volume (V) under constant temperature; i.e., PV = k, which is a constant.
- What is an excellent illustration of Boyle’s Law?
Ans. Boyle’s law in action is exemplified best by a balloon. By pumping air into the balloon, the rubber walls of a balloon experience pressure, causing the balloon to inflate. Likewise, when you squeeze a balloon, the pressure inside the balloon rises, causing the air inside to rush out.
- Is it possible to verify Boyle’s law experimentally?
Ans. It is possible to prove the law empirically. The syringe-based experimental model and other applications mentioned in the article confirm that Boyle’s Law is true.
- What kinds of questions about Boyle’s law are posed in competitive exams?
Ans. Questions about Boyle’s law are asked in competitive exams like NEET and are based on its definition, graphical representation, and applications. These questions are straightforward to answer. We want you to pay special attention to the graphical representation of the law because it is the source of a huge number of inquiries.