Unit 2.4 – Boyle’s Law 

Boyle’s Law, Charles’ Law and Gay-Lussac’s Law oh my!

The above 3 laws apply to gas particles based on varying 3 variables: pressure, volume and temperature while leaving 1 constant.

In Boyle’s Law, the equation is P1 V1 = P2 V2 but only maintaining a constant temperature.

What does the equation mean?

Visualize a football. If you were to apply pressure to it, it will get smaller. Basically you have just made the volume smaller by applying pressure.

More than just a math equation

Many of us often enjoy the gas laws math operations because we are often guilty of looking at the numbers in the question and plugging the numbers in. But what does this equation mean and why is it important?

The equation is important because of its directly inversely proportional relationship, we can now quantitatively (put into numbers) relate between the amount of pressure and volume.  In other words, if we have the actual amount of pressure and volume, we can calculate the actual amount after the change occurs, such as applying new pressure.

Pressure and volume is an inversely proportional relationship meaning that if one were to decrease, the other would increase.

boyles law

The graph above shows Boyle’s law on the relationship between volume and pressure. You might be wondering, why do I see this graph sometimes?

Boyle.graph

 

Since we know the relationship is an inverse relationship, this simply means that one is proportional to the inverse of the other. If we look at the first graph, that is the graph with the raw data between pressure and volume.  But if we were to change one of the variables to the inverse such as 1/vol and graph the data points, we would see the graph directly above. After all, Boyle’s law is when Pressure is directly proportional to the INVERSE of Volume (or vice versa).

Here’s a great website from Nasa on Boyle’s Law https://www.grc.nasa.gov/www/K-12/airplane/boyle.html

Phet’s awesome simulation of gas laws

Gas Properties