Boyle's Law - Definition, Graph, Applications, Equation and Formula
Boyle’s law is an experimental gas law. Henry Power and Towneley were the first people to discover the relationship between the volume and pressure of a gas. Later on, an Anglo-Irish physicist, philosopher, and chemist named Robert Boyle made an experiment and confirmed his discovery which he later went on publishing its results in the year 1662.
Now, we understood why this law was named Boyle’s law. Moreover, this law can also be called as Boyle-Mariotte law, as this law was reframed by a French physicist named Edme Mariotte in 1679. Boyle’s law is capable of describing how the volume of a gas can change when there is a change in pressure while keeping mass and temperature constant.
Definition of Boyle’s law
Boyle’s law can be stated as follows: the absolute pressure put forth by the provided mass of any particular ideal gas which can be seen inversely proportional to that of the volume it could occupy if the amount of gas and temperature remain constant inside a closed system. Given below is the mathematical expression for Boyle’s law,
P ∝ 1V
Here, P is nothing but the pressure of the gas whereas V is the volume of the gas. This means that for a gas, in case the temperature is maintained at a constant point while also keeping the number of moles of gas as constant, then if the pressure is increased, the volume will see a decrement. On the other hand, if the pressure is being decreased, then the volume can see an increase.
While removing the equation of proportionality, the equation becomes,
P V=k
Where k can be regarded as the constant. Therefore, this law is expressed as,
Graphical Representation of Boyle’s Law
The following are some of the graphical representations of Boyle’s law,
- 1. Graph of pressure vs volume
A graph can be plotted while taking the volume along the x-axis whereas pressure along the y axis.
Every curve can be seen as a rectangular hyperbola and they correspond to various constant temperatures and can be termed as an isotherm for that curve. Isotherm means plotting the values of constant temperature. It is common from the graphical representation that higher curves denote higher temperatures. Also, if pressure seems to be halved, then this can lead the volume of the gas to be doubled.
- 2. Graph of pressure vs reciprocal of volume
From the graph of pressure vs reciprocal of volume, it is clear that the straight line obtained can confirm that
P ∝1V.
- 3. Graph of product of pressure and volume vs pressure
This graphical representation talks about how the parallel lines drawn at a certain temperature of the gas are the product of its volume while keeping the corresponding pressure constant.
Application of Boyle’s Law
Boyle’s law can be seen in daily life activities. A very interesting example of Boyle’s law would be the human breathing system. Along with this, some of the day-to-day applications are as follows
- Working of syringe – Boyle’s system has its application in the working principle of a syringe. It is when we try to pull the plunger contained inside the syringe, it enhances the volume in the barrel that produces less amount of pressure inside it, and could result in the form of external fluid and forces to go inside the barrel.
- Bicycle pump – The working procedure of a bicycle pump is purely based on Boyle’s law. It works similarly to that of the syringe that we have discussed above.
- Human breathing – In our body, when we breathe, the lungs expand to make way for the air to circulate (to go out and come in). When this happens, there is an increased volume of the lungs, which reduces the pressure contained in the lungs. This is exactly what happens in Boyle’s law. So, as the pressure present inside the body is relatively lower than that of the surroundings, it allows the outer air to come inside the lungs. This process is called inhalation. In the meantime, during exhalation, the volume inside the lungs decreases while increasing the pressure that causes the air to go out of the lungs.
- Different professions – Boyle’s law can find its applications in space or air domains such as scuba divers and astronauts.