Lab Gas Laws

Gas Laws Demos

The in-person version of this lab has ~ 10 demo stations for which each group of student will rotate through. At each station are instructions. In a best case scenario, each demo should be documented in your lab notebook under the demo name heading. Some demos require additional calculations.

Chapter 5 material: The content associated with these demos comes from all different sections in this chapter. Reference will be made to the section, but you will only be responsible for the specific information discussed in the demo activity.

Diffusion of Gases

Watch this video --> https://youtu.be/Rf9j0ztzcs4

in your notebook...

Write out the reaction that occured...

• what is the molecular mass of HCl -->
• what is the molecular mass of NH₃ -->
• Eq. 5.17 indicate that the rate at which the gases "diffuse" is inversely proportional to the molecular mass. This means that because HCl is heavier than NH₃, it will move slower and as a result the NH₄Cl formed will not be in the center, but closer to the HCl side due to the fact that NH₃ is moving faster. If you plug your molecular masses into Eq 5.17, you will see the the ratio r(NH₃)/r(HCl) ~ 1.4, so the NH₃ travels 1.4x the distance that HCl would have traveled.

Take home: the heavier the gas the slower it moves, the lighter the gas the faster it moves.

The Amazing bottle

Watch this video --> https://youtu.be/pDtWRrGj6qk

This is a fun demonstration that you could do at home if you had a balloon...try it (not required)...thicker plastic bottles work the best.

in your notebook...

Draw a detailed picture of the "amazing bottle."

Take home: If you try and blow up a balloon inside of a bottle, the pressure inside of the bottle will increase very quickly since you are decreasing the volume of the bottle very rapidly. If the pressure inside the bottle is allowed to return back to room pressure (by putting a small hole in the bottle) then it appears that you can blow it up, but this is a trick. As shown in the video, if you cover the hole after blowing up the balloon, then you will create a vacuum (low pressure) inside of the bottle preventing the balloon from deflating. You can even "such up," as opposed to "blow up" a balloon!

Cloud in a Bottle

Watch this video --> Instant Cloud Science Experiment

This is an interesting demonstration that is really quite complex. I teach the details of this demonstration in my 300-level Physical Chemistry course; it is all about the Joule-Thomson coefficient. In short, when gases under high pressure are allowed to expand quickly to a low pressure, they can either heat up or cool down. In this demo, the gas cools down, the water vapor condenses into tiny droplets and you know this as a cloud.

in your notebook...

header only...with smiley face.

Take home: Weather and chemistry are connected; science is cool!

Liquid Nitrogen

___ Boyle’s Law

___ Charles’ Law

___ Ideal Gas Equation

___ Butane: liquid or gas?

___ Density of Gases

___ Crushing Soda Cans

___ Evacuation – sucking up a balloon

___ Methanol Combustion

___ What is it…a nebulizer?

___ Cartesian Diver