Boyle's Law

Science is a field which gives an opportunity of unlimited exploration even if one restricts himself to a particular domain. Many scientists dedicated their entire lives to this field and contributed towards the evolution of mankind. Robert Boyle was one such scientist. One of his most famous works (Boyle's Law) was that of forming a relation between the volume of a gas and the pressure applied on it. Boyle's Law was a result of dedicated work by Robert Boyle to determine the variation of volume of a gas with the change in pressure. The law holds true as long as the amount of gas and its temperature are kept constant. Robert Boyle stated Boyle's Law and formulated its mathematical equation with the help of multiple observations in the properties of gases and their ideal behavior.

Robert Boyle
Robert Boyle was born on 26th January, 1627 and is considered as one of the founders of modern chemistry. Most of his research was carried out while he was in Oxford and it mostly dealt with the behavior of gases. Besides science, Boyle was also interested in theology and learned various languages like Greek, Hebrew and Syriac in order to enhance his understanding of the scriptures. He also founded the Boyle Lectures to defend Christianity against other religions.

Boyle's Law and its Mathematical Interpretation
Boyle's Law helps to determine the effect on the volume of a gas while changing the pressure applied on it. The amount of gas and temperature should be kept constant while performing the experiment in order to plot the correct relation between pressure and volume. The law states that if the temperature is kept constant, volume of a gas is inversely proportional to the pressure applied. Mathematically the law can be written as:

PV=constant (k)

where,
P=pressure of the system
V=volume of gas
k=a constant value

According to the mathematical interpretation, as long as the temperature of the system does not change, the value of 'k' remains the same and hence Boyle was able to formulate a more generalized equation, which can be written as:

P₁V₁=P₂V₂

where P₁ and V₁ is the initial pressure and volume and P₂ and V₂ is the final pressure and volume. According to this equation, it can be easily seen that if pressure applied on a gas is increased, its volume decreases and if pressure is decreased, the volume increases, in order to keep the value of 'k' constant. Boyle's Law was derived from the kinetic theory of gases assuming an ideal gas. It was also discovered that real gases obey Boyle’s law only at a sufficiently low pressure; as at higher pressures, gases generally show deviation form their ideal behavior.

Example: Suppose the initial volume and pressure of the gas is 3L and 4 atm respectively, then using Boyle's law, the final pressure of gas can be calculated if volume is decreased to 2.5 L. According to Boyle's law,

P₁V₁=P₂V₂
So,
P₂=P₁V₁ / V₂
=> P₂=(3*4) / 2.5=4.8 atm.

Hence the final pressure of the gas is 4.8 atm.

Boyle's Law, Charles's Law and Gay-Lussac's Law together form the combined gas law, and are used for mathematical calculations while carrying out experiments in the laboratory. Besides studying the behavior of ideal and real gases, Robert Boyle also carried out experiments to determine the role of air in allowing sound to travel, the ability of crystals to bend light and the behavior of liquids at rest. Boyle's Law is still one of the very basic laws of chemistry and has helped the scientists in understanding the properties of gases in a better way.