Day 3: The Ideal Gas Law

Heating Can In the Cold Water

The first thing we have done in class was predicting what will happen if a heated can containing water vapor is put in the cold water beaker. 

After Professor Mason performed the experiment, the heated can shrunk as our prediction.

The can shrunk because the hot steam in the can turn into water, and water to be drawn up into the can by the low pressure relative to the outside atmosphere. The only way for the pressure in the can to be equalized so rapidly is for the can to collapse.

Also, this time the can was empty with no water in it. After the can was heated and put in the cold water beaker, the water was sucked up into the can.

Units of Pressure

We tried to write different units of pressure and found 1 atm = 10^5 Pa.

Boyle's Law (P vs. V)

We used  syringe and Logger Pro to measure the graph of pressure from volume 6 cc to 20 cc. 

And we got a inverse fit on the line which pressure = A/V^1+B where A = 651.0 and B = -26.6.

Gay-Lussac's Law (P vs. T)

We predicted the relationship between pressure and temperature to be a linear line.

We started to test if pressure and temperature will be a linear line. Professor Mason started the experiment by heating the flask without measure the pressure. 

The he plotted the first point when he put the flask in the cold water.

He plotted the second point when he put the flask into hot water.

Lastly, he put the flask in room temperature water.

And this is the final graph after the experiment with a lineal slope P = 0.2427T + 93.5

Charles' Law (V vs. T)

Like the previous experiments, we predicted the graph of volume vs. temperature also to be a linear line. We also calculated the unit of A. 

Then Professor Mason performed the experiment to acquire the real volume vs. temperature graph. The same steps as the P vs. T experiment except this time the volume was measured instead of pressure. 

This is the final graph of volume vs. temperature. Pretty much a linear line as we predicted.

The Relationship Between Kb and R

 We used two different forms of ideal gas law: PV = nRT and PV = NKbT to calculate that Kb/R equals the Avogadro's number which is 6.02*10^23 mol

Diving Bell Problem 

 In this practice problem, we solved for the height in the diving bell and the total pressure.

Vacuum Chamber Demos 

We did a vacuum chamber demo which we put a balloon and marshmallows in a chamber. When we put the air inside the chamber, they shrunk; when we pulled the air out, they expand.  

When we drew the air out of the chamber, the marshmallows first expanded. After we turned in back in normal, the marshmallows shrunk and were smaller than the original size.

Balloon Problem

We had another practice problem to use ideal gas law PV = nRT and molar mass conversion to calculate the mass of helium in a big balloon. 

Conclusion

Today, we have done three activities about proving Boyle's law, Gay-Lussac's Law, and Charles' Law. We also did the balloon and marshmallow in the chamber activity to see the effect of pressure. We also did several problems on ideal gas law.