Gas Properties

Objective:

In this exercise you will investigate some thermometric properties of gases.
The ideal gas law states that for a fixed volume of an ideal gas (PV/T) = nR = constant.  Here P and V are the pressure and volume of the gas at absolute temperature T.  Theoretical derivations of the ideal gas law neglect the forces that the gas molecules exert on each other.  Real gases therefore do not strictly obey the ideal gas law.  However, at sufficiently low densities, intermolecular forces do not play a significant role and the ideal gas law becomes increasingly accurate.  For instance, at 20 atm pressure and room temperature, the volume of 1 mole of oxygen gas is about 2.3% smaller than predicted by the ideal gas law, but at 1 atm pressure the volume is only about 0.13% smaller. 

bulletIf the temperature T is constant the ideal gas law yields Boyle’s law, PV = constant (at constant T). 
bulletIf the pressure is held constant, the ideal gas law yields Charles's law, V/T = constant (at constant P).

Procedure:

Open a Microsoft Word document to keep a log of your experimental procedures and results.  Complete all the tasks (in blue).  Answer all questions.

Use an on-line simulation from the University of Colorado PhET group to verify Boyle's law and Charles' law.
Link to the simulation: Gas_Properties

(a)  Explore the interface!  (Click "Help" for hints.)

bulletYou can pump two types of molecules into the chamber.
bulletYou can specify constant volume, pressure, or temperature.
bulletYou can work in an environment with or without gravity.
bulletYou can heat up the gas in the chamber.
bulletYou can use various measuring tools. (Explore what they can be used for.)

(b)  Reset the simulation, choose constant volume and a gravity-free environment and add gas to the chamber at 300 K until the pressure is between 1 and 2 atm.
Switch to constant temperature and verify Boyle's law.  Boyle’s law states  that PV = constant for constant T, or P = constant/V.
A plot of P versus 1/V should yield a straight line.  If it does, you have verified Boyle’s Law.
Construct an appropriate data table and plot with at least 6 data points.  Paste them into your Word document.  Add comments.  Did you verify Boyle's law?
[The volume of the box is V = length * width * height.  Width and height are fixed, so  V = constant*length.  Let us set the constant to 100 nm2.  The length can be measured with the ruler in units of nanometer (nm).]

(c)  Switch to constant pressure and verify Charles' law.  Charles' law states V = constant * T for constant P, where T is the absolute temperature.  A plot of V versus T should yield a straight line.  If it does, you have verified Charles' Law.
Construct an appropriate data table and plot with at least 6 data points.  Paste them into your Word document.  Add comments.  Did you verify Charles' law?

(d)  Reset the simulation, choose constant volume and a gravity-free environment and add two species gas to the chamber at 300 K until the pressure is between 1 and 2 atm.  Compare the average speeds of the two types of particles.  Explain your results.

(e)  In an environment with lots of gravity explore how the pressure varies with height.
Construct an appropriate data table and plot.  Paste them into your Word document.  Add comments.

To earn extra credit add your name and e-mail address to your log that contains your data tables, graphs, comments and answers.
Save your Word document (your name_exm2.docx, go to Blackboard, Assignments, Extra Credit 2, and attach your document.