How Does the Ideal Gas Law Explain the Crushing of a Can?

[Kelly-Anne]

Homework Statement

Fill the sauce pan with tap water. Set it close to the stove.
Place about 2 tablespoons of water into the empty can.
Heat the can on the stove until the water inside boils. This will not take long. You will see water vapor coming out of the top of the can when it is boiling.
Pick up the can with the tongs, immediately turn it upside down, then place the can in the water and pan.

Homework Equations

1. What happened when you put the can in the water?

2. Why did this happen? Make sure you relate why this happened to the changes in pressure inside and outside the can.

3. Why did you have to turn the can upside down?

4. What gas law would account for what happened?

5. Explain how your choice of this gas law is supported by your observations.

 

[Borek]

So, what you have seen when doing the experiment?

 

[Blueshift5]

1. When the can was placed in the water, the water level in the can rose and the can was crushed.

2. This happened because the water vapor inside the can condensed and turned back into liquid, creating a vacuum inside the can. This vacuum created a difference in pressure between the inside and outside of the can, causing the higher outside pressure to crush the can. This is known as the "can crush" experiment and demonstrates the relationship between pressure and volume.

3. The can had to be turned upside down so that the open end was submerged in the water. This allowed for the water vapor to condense and create a vacuum inside the can, rather than just releasing the excess pressure from the open end.

4. The ideal gas law, PV=nRT, would account for what happened. This law describes the relationship between pressure (P), volume (V), number of moles (n), temperature (T), and the universal gas constant (R).

5. The ideal gas law is supported by our observations because as the water vapor condensed and the temperature remained constant, the volume inside the can decreased, causing an increase in pressure. This increase in pressure is what ultimately crushed the can, demonstrating the inverse relationship between volume and pressure at a constant temperature.