Tag: Gas Law

People of Interest: Robert Boyle – 1627 to 1691

Published on by johnball2014Leave a comment

Being in the compressed air industry for over 35 years, you come across many interesting people from the past that have created laws that we are still using today.   Robert Boyle is one of those people.  He was born on January 25, 1627 in Lismore Castle in Ireland.  He published the book “The Sceptical Chymist” in 1661, and many considered his work to be the foundation of modern chemistry.  He dabbled in many areas of study, but with a young university student, Robert Hooke, they found Boyle’s Law.

 The experiment was performed using a ‘J’ shaped glass tube sealed on the shorter leg, and open to atmosphere on the longer leg.  Mercury was poured into the tube, such that the level was equal on each side. The volume of the trapped air was noted. Additional mercury was poured into the tube, and it was observed that the mercury did not stay level, and measurements of the heights of each tube leg were recorded.  The height difference of the mercury is effectively a measure of the pressure of the trapped air.  Through the experiment and the data, Boyle discovered a relationship between the volume and the pressure of air.  The data as published, is shown below.

Boyle noticed the pressure times the volume of air for the initial condition equaled the pressure times the volume at any other mercury height.  So, the pressure is proportional to the inverse of the volume, Equation 1.

Equation 1: P ∝ 1/V

Or P * V = k (a constant)

For comparing the same substance under two different sets of conditions, Boyle’s law can be expressed as Equation 2.

Equation 2:  P1 * V1 = P2 * V2

Equation 2 looks very familiar.  One of Boyle’s most famous discoveries was to become the first of the gas laws, relating the pressure of a gas to its volume. Combining Boyle’s Law with Charles’s Law, Gay-Lussac’s Law, and Avogadro’s Law; you will have the basis and creation of the ideal gas law;

Equation 3:   P * V = n * R * T

which includes the major factors that affect a gas; temperature, pressure, volume, the amount of the gas, and the ideal gas constant.

Robert Boyle passed away on December 31st, 1691, and from his work, EXAIR uses the pressure and volume of compressed air for our Intelligent Compressed Air® Products to make them efficient, safe, and effective.  If you would like to speak more about how EXAIR can benefit your pneumatic system, one of our Application Engineers can help you determine the best solution.

John Ball
Application Engineer
Email: johnball@exair.com
Twitter: @EXAIR_jb

Robert Boyle image courtesy of Skara Kommun, Creative Commons License

Robert Boyle the Father of Chemistry and Boyles Law

Published on by codybiehleLeave a comment

Robert Boyle, one of the founding fathers of modern chemistry and a man who changed the very way we look at scientific research. From the Scientific Method to the very laws that govern gasses, Robert Boyle was able to change the very way we look at life and solve our problems. One could say that Robert Boyle didn’t really have what you would call a humble beginning; he was born in January 1627 to the 1st Earl of Cork Richard Boyle and his wife Catherine Fenton at Lismore Castle in Ireland. When he was only 8 years of age, he was sent off to Eton College in order to study under a private tutor. In 1641 Robert would spend the winter in Florence Italy studying the “paradoxes of the great star-gazer” Galileo Galilei.

Robert Boyle

Starting in mid-1644 Robert would make his residence in Dorset England were he conducted many experiments and from then devote his life to research. In 1654, Boyle would move to Oxford from Ireland in order to further pursue his studies in chemistry. It was here in 1657 that he would read about Otto von Guericke’s air pump, and would set out to improve the system along with Robert Hooke. In 1659 the “Pneumatic Engine” would be completed and he began a series of experiments on the properties of air. He would further go on to coin the term factitious airs which is a term used to describe synthetic gases after isolating what is now understood to be hydrogen.

Though he was primarily interested in chemistry, one of Boyle’s most famous discovery was what is now known as the first of the gas laws, rightfully named Boyles’s Law.  Boyle’s Law defines the relationship between pressure and volume in a closed area given the mass of an ideal gas. Boyle and his assistant Robert Hooke used a closed J-Shaped tube and poured mercury in from the open side, forcing the air on the other side to contract under the pressure. After repeating this using several different amounts of mercury Boyle deducted that the pressure of a gas is inversely proportional to the volume occupied by it.

Boyle’s Law

In 1669 his health, although which was never very good, began to fail seriously and he withdrew from the public. In his later days he would propose some important chemical investigations which he wanted to leave as a sort of legacy for those who would were also “Disciples of the Art”, essentially future chemists. On the winters day on December 31, 1691 Robert Boyle took his final breath. In his will Robert Boyle left a series of lectures known as the Boyle Lectures the talked about the relationship between Christianity and today’s science.  

Here at EXAIR we use Boyle’s Law everyday as nitrogen, oxygen, and hydrogen (the three main elements that make up air) are all considered ideal gas. This means that all of our products are governed by the relationship between pressure and volume.

If you have questions about any of our quiet EXAIR Intelligent Compressed Air® Products, feel free to contact EXAIR or any Application Engineer.

Cody Biehle
Application Engineer
EXAIR Corporation
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Robert Boyle image courtesy of Skara Kommun, Creative Commons License

Robert Boyle And The Scientific Method

Published on by Russ BowmanLeave a comment

How do we know something is true? In grade school, you may remember being taught a process by which an observation elicits a question, from which a hypothesis can be derived, which leads to a prediction that can be tested, and proven…or not) These steps are commonly known as the Scientific Method, and they’ve been successfully used for thousands of years, by such legendary people of science as Aristotle (384 – 322 BC,) Roger Bacon (1219 – 1292,) Johannes Kepler (1571-1630,) Galileo Galilei (1564-1642) and right up to today’s scientists who run the CERN Large Hadron Collider.  The collider is the largest machine in the world, and its very purpose is the testing and proving (or not) of hypotheses based on questions that come from observations (often made in the LHC itself) in ongoing efforts to answer amazingly complex questions regarding space, time, quantum mechanics, and general relativity.

The Scientific Method is actually the reason (more on this in a minute) for the name of a fundamental law of physics: Boyle’s Law.  It states:

“For a fixed amount of an ideal gas kept at fixed temperature, pressure and volume are inversely proportional.”

And can be mathematically represented:

PV=k, where:

  • P = is the pressure of a gas
  • V = is the volume of that gas, and
  • k = is a constant

So, if “k” is held constant, no matter how pressure changes, volume will change in inverse proportion.  Or, if volume changes, pressure will change in inverse proportion.  In other words, when one goes up, the other goes down.  It’s also quite useful in another formulaic representation, which allows us to calculate the resultant volume (or pressure,) assuming the initial volume & pressure and resultant pressure (or volume) is known:

P1V1=P2V2, where:

  • P1  and P2 are the initial, and resultant, pressures (respectively) and
  • V1  and V2 are the initial, and resultant, volumes (respectively)

This is in fact, what happens when compressed air is generated, so this formula is instrumental in many aspects of air system design, such as determining compressor output, reservoir storage, pneumatic cylinder performance, etc.

Back to the reason it’s called “Boyle’s Law” – it’s not because he discovered this particular phenomenon.  See, in April of 1661, two of Robert Boyle’s contemporaries, Richard Towneley and Henry Power, actually discovered the relationship between the pressure and volume of a gas when they took a barometer up & down a large hill with them.  Richard Towneley discussed his finding with Robert Boyle, who was sufficiently intrigued to perform the formal experiments based on what he called “Mr Towneley’s hypothesis.”  So, for completing the steps of Scientific Method on this phenomenon – going from hypothesis to law –  students, scientists, and engineers remember Robert Boyle.

Russ Bowman
Application Engineer
EXAIR Corporation
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IMGP6394 image courtesy of Matt Buck, Creative Commons License

People of Interest: Robert Boyle – January 25, 1627 – December 31, 1691

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Robert Boyle was born on January 25, 1627 in Lismore Castle, County of Waterford, Ireland.  He was an Anglo-Irish natural philosopher, chemist, physicist and dabbled in many other areas of study. He published the book The Sceptical Chymist in 1661, and many consider him and his work as the foundation of modern chemistry.  He was a very devout Anglican, and published numerous works in this area as well.

Robert Boyle

One of Boyle’s most famous discoveries was to become the first of the gas laws, relating the pressure of a gas to its volume. With Robert Hooke, a young university student as his laboratory assistant, Boyle began experimenting with air.  Together they made their first great discovery, now known as Boyle’s Law.

J-Tube 2
Boyle used a ‘J’ Tube – Sealed on the Short End, and Open at the Long End

The experiment was performed using a ‘J’ shaped glass tube sealed on the shorter leg, and open to atmosphere on the longer leg.  Quicksilver (mercury) was poured into the tube, such that the level was equal on each side. The volume of the trapped air was noted. Additional mercury was poured into the tube and it was observed that the mercury did not stay level, and measurements of the heights on each tube leg were recorded.  The height difference of the mercury is effectively a measure of the pressure of the trapped air. Boyle, through the experiment and the data,  discovered a relationship between the volume and the pressure of air.  The data as published, is shown below.

Boyle's Data

Boyle noticed the pressure times the volume of air for the initial condition equaled the pressure times the volume at any other mercury height.

Known as Boyle’s Law – P ∝ 1/V,      pressure is proportional to the inverse of the volume

Alternately, PV = k,       pressure times volume is equal to a constant

For comparing the same substance under two different sets of conditions, the law can be expressed as P1V1 = P2V2

Of note is that Boyle’s Law, combined with Charles’s law and Gay-Lussac’s Law formed the combined gas law, and in combination with Avogadro’s law is the basis for the ideal gas law – PV=nRT, which include temperature, the amount of the substance, and the ideal gas constant to the mix.

It is noted that Boyle credited fellow scientist Richard Towneley for making the connection between the pressure of a gas and volume, but Boyle’s experiments and observations using the ‘J’ tube confirmed Towneley’s predictions, and the rest as they say is history.

If you would like to talk about compressed air or any of the EXAIR Intelligent Compressed Air® Products, feel free to contact EXAIR and myself or one of our Application Engineers can help you determine the best solution.

Brian Bergmann
Application Engineer

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Experiment Data from the book New Experiments Physico-Mechanicall, Touching the Spring of the Air, and Its Effects (1660)