Steven is a 30-something futurist, father, and self-taught science nut.
What Is Boyle's Law and Equation?
In 1662, Robert Boyle discovered the volume and pressure of gasses are inversely proportionate when held at a constant temperature. Put simply, when volume rises, pressure drops, and vice versa.
The mathematic equation is equally as simple.
PV = k
In this equation, (P) represents pressure, (V) represents volume, and (k) is a constant.
This has become a basic principle in chemistry, now called "Boyle's law," and is included as a special case in the more general ideal gas law.
How Did Boyle Come up With His Law?
Using a vacuum pump invented by Otto von Guericke in 1654, Boyle carried out experiments investigating the properties of air and the vacuum.
During his experiments, he stumbled upon the greatest achievement of his life. By using a J-shaped glass tube that had air at the tip of the curve, Boyle altered the weight of the air using mercury and, as he did so, he saw that the space of air at the tip of the curve became smaller. He discovered that when you increase pressure on a gas, the gas's volume predictably shrinks.
Why Is Boyle's Law Important?
Boyle's law is important because it tells us about the behavior of gasses. It explains, with certainty, that the pressure and volume of gas are inversely proportional to one another. So, if you push on gas, its volume becomes smaller and the pressure becomes higher.
Examples of Boyle's Law in Life
You have probably been well-acquainted with Boyle's law for most of your life without realizing it. We experience examples of this law on a regular basis. The first example is a rather common one, assuming you have filled a tire with air before.
Generally, you fill a tire with somewhere between 30 to 35 PSI (pounds per square inch) of compressed air. This is a measurement of pressure. As you put more and more air into the tire, you are forcing all the gas molecules to get packed together, reducing their volume and increasing the pressure pushing on the walls of the tire. As long as the air temperature remains the same, you are experiencing a real life example of this law.
Other examples include:
Real-World Applications of Boyle's Law
- Spray paint
- The syringe
- The soda can
- The bends
Read on for descriptions of the examples listed above.
1. Spray Paint
While there are a couple different types of aerosol cans, some being a little more elaborate than other, they all rely on the same basic principle: Boyle's law.
Before you spray a can of paint, you are supposed to shake it up for a while as a ball bearing rattles around inside. There are two substances inside the can: one is your product (paint for example), and the other is a gas that can be pressurized so much that it retains a liquid state, even when it is heated past its boiling point.
This liquefied gas has a boiling point far below room temperature. Because the can is sealed, the gas is prevented from boiling and turning into a gas. That is, until you push down the nozzle.
The moment the nozzle of a spray paint can goes down, the seal is broken and the propellant instantly boils, expands into a gas, and pushes down on the paint. Under the high pressure, the paint is forced out of the nozzle as it attempts to reach an area with lower pressure.
2. The Syringe
This mechanism is far more simple than a can of spray paint. Syringes of all types utilize Boyle's law on a very basic level.
When you pull the plunger out on a syringe, it causes the volume within the chamber to increase. As we know, this causes the pressure to do the opposite, which then creates a vacuum. When a syringe is empty, the vacuum within the chamber sucks fluid in through the needle.
3. The Soda Can or Bottle
Typically when we open a bottle of soda, we slowly turn the cap to allow the air to escape before we completely remove the lid. We do this because we've learned over time that twisting it open too fast causes it to fizz up and spill all over. This happens because the liquid is pumped full of carbon dioxide, causing it to bubble up as the CO2 makes its escape.
When a soda bottle is filled, it is also pressurized. Much like the aerosol can mentioned earlier, when you slowly open the cap, the gas is able to increase its volume and the pressure decreases.
Normally you can let the gas out of a can or bottle release cleanly, but if the bottle is shaken up and the gas is mixed into the liquid, then you may have a mess on your hands. This is because the gas trying to escape is mixed into the fluid, so, when it does escape, it brings the foamy fluid out with it. Pressure in the bottle goes down, volume of the gas goes up, and you have yourself a mess to clean up.
4. The Bends
Any properly trained scuba diver knows when they are ascending from deep waters, a slow ascension is critical. Our bodies are built for and accustomed to living in the normal pressure of our lower atmosphere. As a diver goes deeper underwater, that pressure begins to increase. Water is heavy, after all. With the increasing pressure causing a decrease in volume, nitrogen gasses begin to be absorbed by the diver's blood.
When the diver begins his ascent and the pressure is lessened, these gas molecules begin to expand back to their normal volume. With a slow ascent, or through the use of a depressurization chamber, those gasses can work their way back out of the bloodstream slowly and normally. But if the diver ascends too quickly, the blood in their vains becomes a foamy mess. The same thing that happens to a foamy soda is what happens to a diver's bloodstream during the bends. On top of that, any built up nitrogen between the diver's joints will also expand, causing the diver to bend over (hence its name) in severe pain. In the worst cases, this sudden depressurization of the body can kill a person instantly.
The Cartesian Diver: Build Your Own Example of Boyle's Law
By now you either have a basic understanding of Boyle's law and how it can be applied to the real world, or you're suddenly afraid to go swimming.
Either way, this last example of Boyle's law in action is something you can build yourself! First, you need a small list of supplies:
- One transparent 2-liter bottle
- One small glass dropper
Once you've managed to gather these supplies, follow the steps below.
How To Build a Cartesian Diver
- Add water until the 2-liter bottle is full.
- Take your eyedropper, the "diver," and fill it with just enough water so that the top of the dropper is just buoyant enough to float on top of the water.
- Apply the lid to the 2-liter bottle. It must be airtight!
- Squeeze the bottle.
If you have successfully followed the instructions, your Cartesian diver should dive to the bottom as you squeeze the bottle. That's Boyle's law in action!
When you squeeze inward, you are reducing the volume of the bottle. As we know, this reduction in volume increases the pressure.
This increase in pressure pushes against the water, forcing more water up into the eyedropper. This additional water decreases the diver's buoyancy, causing it to "dive" to the bottom. Stop squeezing the bottle, and your diver will ascend back to the water's surface.
DIY Cartesian Diver (Video)
What Is the Ideal Gas Law?
Since it is hard to exactly describe a real gas, scientists created the concept of an ideal gas. The ideal gas law refers to a hypothetical gas that follows the rules listed below:
- Ideal gas molecules do not attract or repel each other. The only interaction between ideal gas molecules would be an elastic collision with each other or with the walls of the container.
- Ideal gas molecules themselves take up no volume. While the gas takes up volume, the ideal gas molecules are considered point particles that have no volume.
There are no gasses that are exactly ideal, but there are many that are close. This is why the ideal gas law is extremely useful when used as an approximation for many situations. The ideal gas law is obtained by combining Boyle's law, Charle's law, and Gay-Lussac's Law, three of the major gas laws.
What Is Charle's Law?
Charle's law, or the law of volumes, was discovered in 1787 by Jaques Charles and states that for a give mass of an ideal gas at constant pressure, the volume is directly proportional to it's absolute temperature. This means that as the temperature of a gas increases, so does its volume.
V / T = k
The equation of Charle's law is written above, with (V) representing volume, (T) representing temperature, and (k) representing a constant.
What Is Gay-Lussac's Law?
Gay Lussac's law, or the pressure law, was discovered by Joseph Louis Gay-Lussac in 1809 and states that, for a given mass and constant volume of an ideal gas, the pressure exerted on the sides of its container is directly proportional to its absolute temperature. This means that pressure indicates temperature.
P / T = k
The equation of Guy Lussac's law is written above, with (P) representing pressure, (T) representing temperature, and (k) representing a constant.
How Does Boyle's Law Relate to Breathing?
When it comes to the effects of Boyle's law on the body, the gas law specifically applies to the lungs.
When a person breathes in, their lung volume increases and the pressure within decreases. Since air always moves from areas of high pressure to areas of low pressure, air is drawn into the lungs.
The opposite happens when a person exhales. Since the lung volume decreases, the pressure within increases, forcing the air out of the lungs to the lower pressure air outside of the body.
What Are the Two Stages of the Breathing Process?
The breathing process, sometimes called respiration, can be simply broken down into two stages: inhalation and exhalation.
During inhalation, also called inspiration, the diaphragm contracts and pulls downward and the muscles between the ribs contract and pull upward, increasing the volume of the lung cavity and decreasing the pressure within. As a result, air rushes in to fill the lungs.
During exhalation, also called expiration, the diaphragm relaxes and the volume of the lung cavity decreases while the pressure within increases. As a result, air is forced out.
How Do You Know When to Breathe?
Breathing is controlled by a respiratory control center at the base of your brain. This center sends signals down your spine that ensure your breathing muscles in your lungs contract and relax regularly.
Your breathing can change depending on how active you are, as well as on the condition of the air around you. Other factors that may affect your breathing include your emotions or deliberate actions such as holding your breath.
A Final Word
I did leave a certain application of Boyle's law out of this list that is used far more than any of the above examples. This system is directly powered by the rules of Boyle's law, and is a device you use every day, everywhere you go.
What is it? Comment your answer below!
© 2012 Steven Pearson
Person is my name on December 10, 2019:
This help me in my homework. I understand now thanks. hahaha
Zeinab Maher on April 21, 2019:
Awesome, I need your application, Please!
Mohammad bulama Abbayo on February 28, 2019:
i give my great greeting to all member, s of this group
reee on January 31, 2019:
meme on January 31, 2019:
aleum on January 17, 2019:
actually this hub is really helpful
ethan on November 29, 2018:
im watching youtube every one lol im laghing
Vedu on October 20, 2018:
Ayushi sharma on September 19, 2018:
Sameer on July 03, 2018:
Thanks it was very helpful to me
Jim H. on June 30, 2018:
Sandra on June 16, 2018:
boyles law is stupid because the more laws the more i have to study bye felcia fk life and school and everyhing else with it
Tyron Smith on May 22, 2018:
I really enjoyed these examples!
tanveerhussalvi on May 14, 2018:
you have done an excellent job in this article! you may check also
Boyle's law formula derivation and examples in daily life
Steve on April 06, 2018:
Your example of the tire is wrong. It is a tire, there is no change to the volume. In that instance you are simply increasing the pressure thanks to fluid dynamics flow, causing the density of the fluid within the volume to increase. Again, you are not changing the Volume. More realistically you are slightly increasing the volume of the tire thanks to the pressure, until you pressurize to rupture.
Murad on March 25, 2018:
More examples of Boyle's law
april igpas on March 04, 2018:
Thanks for this!!
Tony Q. on February 20, 2018:
gg no re on February 14, 2018:
i don't understand or comprehend human logic
narwhal on February 07, 2018:
I still don't get what boyle's law is
Laura on January 27, 2018:
This is all completely wrong. Boyle's law only applies to a given mass of gas - typically in a closed system.
Javier on January 24, 2018:
Thanks this article help me in my homework
Scott Beesley on January 23, 2018:
Warriors BLEW 3-1 Lead
Rianne Arellano Estojero on January 16, 2018:
How many examples in thereBoyle's Law ?
Anna Preston on November 08, 2017:
Good Job! Excellent page!
Let us copy paste on October 30, 2017:
No copy paste? I have to do a FACT SHEET!
proud kannadiga on October 18, 2017:
a on October 14, 2017:
boss on August 10, 2017:
Woah dude on May 23, 2017:
Ohh on May 18, 2017:
email@example.com on May 14, 2017:
A vertical tank of 20ft. dia. as tall as the average tidal range in the Bay of Fundy (say 25ft.) Fixed to the sea bed with a sluice gate open at the bottom, and the top of the tank sealed, What would the air pressure be when it was high enough to prevent more water entering?
Percy on May 04, 2017:
I think the mystery use is us breathing! It goes with us wherever we go.
Genie on April 23, 2017:
This helped me a lot thanks a lot to the ones who did this piece of art.
Paccy on April 20, 2017:
Thank you for this site, you helped in my assignment!!
Auswin on April 05, 2017:
Thanks, this helped me in my physics homework for me.....
cyrene on February 05, 2017:
how does boyle's law applied to medical respirator? please answer
Steven Pearson (author) from Bonney Lake, WA on January 31, 2017:
No, while the volume does increase - the pressure increases faster than the volume. The tires to stretch a very tiny amount, but the air inside is becoming more and more dense. The volume of the gas itself is decreasing (inside the tower) even though the volume of the tire as a whole may be increasing a small bit.
(It is important to realize the difference between the volume of a container, and the volume of individual molecules of gas.)
Nicole on December 12, 2016:
I think that this is so helpful and I hope you post more things that will be this helpful. When you told me examples of Boyle's Law that was the most helful part. Voted up and helpful : )
LarryFranck on November 21, 2016:
Cartesian Diver: If you don't have a medicine dropper, you could just use a ketchup packet instead.
Fill your bottle almost full with water, throw your ketchup packet in, and close the lid tight. Works just as good.
PracticalTeacher on November 02, 2016:
curious_me: You are right in pointing out that filling air into the air is an example that is more closer to Avogadro's law than Boyles Law. When air is pumped into a tire the volume increases following avogadro law which says that greater the amount (moles) of air, greater the volume. I think what the author is trying to get at is that when you pump air into the tires, the air outside (wherever it was initially) is getting squeezed into a smaller volume (ie. tire) and the air in the tire certainly is at a higher pressure than before.
kd on February 09, 2016:
thank you for this site :) I've solved my homework.
Aidan Kittilstved on October 12, 2015:
I think the Mystery Use is the oil storage/injection of a car
Melanie from Midwest, USA on August 07, 2015:
Awesome idea to show real life examples. It always helps me to see concrete examples of ideas that are being taught. Amazing hub! I would love to see more science hubs like this!
marwa abdallah on July 13, 2015:
Loved the way u make everything appear super simple thanx alot for simplifying my assignment:)
Scott on July 08, 2015:
A great article indeed to satisfy the student and the old, old, student too!
Steven Pearson (author) from Bonney Lake, WA on July 06, 2015:
Oh, look at that. Didn't even notice I got HOTD until I was reading these comments lol.
MsLizzy - the correct answer was posted below by Arvedui - it is your lungs ;-)
Liz Elias from Oakley, CA on July 01, 2015:
Congrats on HOTD! Most interesting. I had never heard of Boyle's Law, although you are correct in its daily effects.
Perhaps you can explain, however, why, if a can of soda pop (only works on CANS, not plastic bottles) gets accidentally jostled just before you open it, by sharply rapping your finger tip on top of the can a few times, you can avoid that explosive event upon popping the top open?
As for the device we use daily wherever we go, I'm going to guess it has to do with cars, and either the carburetor or fuel-injection system.
Voted up ++
Kristen Howe from Northeast Ohio on July 01, 2015:
Though I've read this hub a while ago, congrats on HOTD!
vasantha T k from Bangalore on July 01, 2015:
Very useful hub for the students and good examples given. Voted up!
RTalloni on July 01, 2015:
Congrats on your Hub of the Day award for an interesting post that includes a neat science experiment!
Mary Hyatt from Florida on July 01, 2015:
Congrats on your HOTD~ Very interesting, and I voted it as such. You explained Boyle's Law so I could understand the concept. Thanks.
Kristen Howe from Northeast Ohio on April 21, 2015:
This was real interesting to know about Boyle's Law, since I never took chemistry in school. Real great information to know about it. Voted up and useful!
Tolovaj Publishing House from Ljubljana on April 02, 2015:
Boyle's law is one of the basic laws in natural sciences, and I think everybody should know it and understand it. It's great to see an explanation with so many real life examples. Great job!
Dan Hath on March 21, 2015:
By the way, great work! I enjoyed your approach in explaining Boyle's law and the many examples that helped me wrap my head around the concept. Sorry for the double post, I had issues going to edit my post so I could add an extra comment in.
Dan Hath on March 21, 2015:
I can't remember what law it is, but Boyle's law sounds like what I was taught takes place in the combustion chamber of a motor. It is a law that has to do with the pressure of the gas air mixture progressively getting higher (and hotter) as the piston of a motor compresses the mixture before it combusts. Diesel motors take advantage of the law as they don't have spark plugs but glow plugs. The intense compression ratio heats up the mixture causing it to ignite near the top dead center cycle of the piston. If it's not Boyle's law, then I am curious to find out what it is. I am also very curious what you are hinting at. As my solution is what takes place in a combustion chamber of an internal combustion motor.
ramya on March 04, 2015:
mehmood on February 21, 2015:
thanks a lot ...what a simple description,it helped me a lot for my assignment.
Steven Pearson (author) from Bonney Lake, WA on January 05, 2015:
I suppose the wording can be a bit funny. "Volume" in this case isn't necessarily referring to the amount of space inside the tire - but the volume of the gas molecules. As you push more and more air into the tire, the gas molecules are being compressed, thereby reducing the volume of each molecule of gas (not the tire itself), which creates a higher air density.
curious_me on January 02, 2015:
Hi! I liked your article :) It makes science a lot practical to know :) However, I cannot visualize much how filling up tires demonstrates Boyle's Law. How can the volume reduce as pressure is increased? The expansion of the tire indicates increase in volume, right? If this is so, then as air is added to the tire, volume increases and pressure increases as seen in the gauge reading, which defies Boyle's Law. My question is how do I reconcile these contradicting views. Thanks! :)
medini on December 22, 2014:
Thanks for this examples of boyls law ut had helped me a lot :-)♡cool yar♡♡♡
deepthiveera from Cumbum, Tamil Nadu, India on March 31, 2014:
Very interesting to read all those good examples for Boyle's law. Thank you mattforte, for sharing this scientific truth with nice photos and explanations. Voted Up!
blaze on December 04, 2013:
thakxxx because of this article i can already answer
YaraMAriano on February 26, 2013:
Chemistry is everywhere around the globe. Very useful :)
Cuttler from HubPages on February 02, 2013:
interesting...so much to share with my students here. got just what i needed. thank you for sharing
Michele on December 18, 2012:
Steven Pearson (author) from Bonney Lake, WA on October 14, 2012:
Lungs absolutely right! Somebody finally got it! :)
Arvedui on October 14, 2012:
jea alvior on September 28, 2012:
thank you po dahil dito may assignment na ako!!
Cynthia Calhoun from Western NC on April 06, 2012:
Let's see...a system you left out...hyperbaric chamber? Osmosis that happens in the body, you know with the sodium-potassium pumps? The beating heart and the pressure it exerts to make blood pressure?
Anyway, great hub. You could be a physics teacher. I remember doing a unit on Boyle's Law. I don't remember the experiments we did, but I do remember making sine and cosine waves with soda bottles dangling in the air, throwing bowling balls off of school buildings and using a Van der Waal's generator (I think that's how it's spelled) to "electrocute" ourselves. Hehe. Great hub...you brought back lots of memories. :)
Steven Pearson (author) from Bonney Lake, WA on April 02, 2012:
Nothing to do with a car ;-)
Woops! It was a NASA technician, not an astronaut. My mind was elsewhere as I wrote that apparently. ADHD ftw!
Yes, science is a wonderful thing, and most of it is a lot easier than people generally believe. If we teach concepts, rather than extreme detail and advanced mathematics, then it becomes amazingly simple.
Peggy Woods from Houston, Texas on April 02, 2012:
It is obvious that you really do like science which I read in your profile. Thanks for the primer on Boyle's Law. Voted up and interesting.
scottcgruber from USA on March 31, 2012:
Interesting stuff! I hadn't heard about the astronaut who was exposed to space vacuum - who was it?
A more tragic example was Soyuz 11 - three cosmonauts died when their capsule depressurized before reentry.
Lisa from WA on March 31, 2012:
I'm not sure what the last example could be. Maybe something to do with a car?
Anyway, I really liked this article. It's simple, easy to follow, and reminds me of chemistry class in the good old days of highschool/community college. Voted up and useful :)