Gas Law Simulation Inquiry

Purpose: To determine the mathematical relationships between the various properties of gasses.

Resources: Gas Properties Simulation from PhET

http://phet.colorado.edu/simulations/sims.php?sim=Gas_Properties

Assignment: Tire pressures, sinus headaches, cabin pressure in airplanes, even hairspray bottles- all find their explanation in the properties and laws of gas molecules. Four important properties of gases- pressure, temperature, volume, and amount (in moles)- are used to define the behaviors of gas molecules. You and your partner will explore each property and then compare the properties to one another.

Directions: Complete the tasks outlined using the simulator and answer the questions. When opened click on “Measurement Tools“ and select the “Ruler”, “Species information”, and “Stopwatch” buttons.

1.  Under “Gas in Chamber” type in “100” in the “Heavy Species” box Click play at the bottom of the sim and let it run for 10-15 seconds. Record the temperature (T) and pressure (P).

T = K P = Atm

2.  Add heat to the particles. Record temperature and average speed of the particles.

Speed before heated = m/sec Speed after heating = m/sec

3.  What happens to the average speed of the particles as temperature increases?

4.  Reset the simulator and add 50 heavy and 50 light particles. Record the T and volume (V), and speed. To measure the volume, move the ruler so you can measure the size of the box.

T = K V = nm Speed = m/sec

5.  How do the average speeds of the different particles compare at the same temperature?

6.  Reset the simulator and set it to add 50 heavy and 50 light particles.

·  Go to “Constant Parameter” at the top right of the sim and click on “Volume”.

·  Reset the stopwatch and then press “Start.”

·  Now move the arrow in the “Heat Control” box up until it is even with add.

·  Hold the arrow in place for 10 seconds and then press the “Pause” Button on the simulation.

·  Record the numbers in the chart below.

·  Continue doing this for 50 seconds, stopping every 10 seconds.

·  Be sure to press the “Play” Button each time and then the “Start” button on the timer.

Time
(Seconds) / Temperature
(K) / Range of Pressure
(Atm)
10
20
30
40
50

7.  Reset the simulator and set it to add 50 heavy and 50 light particles.

8.  Reset the simulator and set it to add 50 heavy and 50 light particles.

·  Go to “Constant Parameter” at the top right of the sim and click on “Pressure”.

·  Reset the stopwatch and then press “Start.”

·  Now move the arrow in the “Heat Control” box up until it is even with add.

·  Hold the arrow in place for 5 seconds and then press the “Pause” Button on the simulation.

·  Record the numbers in the chart below.

·  Continue doing this for 25 seconds, stopping every 5 seconds.

·  Be sure to press the “Play” Button each time and then the “Start” button on the timer.

Time
(Seconds) / Temperature
(K) / Volume
(nm)
5
10
15
20
25

9.  Reset the simulator and set it to add 50 heavy and 50 light particles.

·  Go to “Constant Parameter” at the top right of the sim and click on “Temperature”.

·  Vary the volume and record the V and P at three more points.

Volume (nm)
Pressure (atm)

10.  Reset the simulator and set it to add 50 heavy and 50 light particles.

·  Go to “Constant Parameter” at the top right of the sim and click on “Volume”.

·  Hold the arrow in place for 5 seconds and then press the “Pause” Button on the simulation.

·  Record the numbers in the chart below.

·  Continue doing this for 25 seconds, stopping every 5 seconds.

·  Be sure to press the “Play” Button each time and then the “Start” button on the timer.

Number of particles
(heavy / light) / Temperature
(K) / Pressure
(Atm)
50 / 50
50 / 100
100 / 50
100 / 100
150 / 150

Analysis and Conclusions

Variables / Constant Parameters / Relationship / Proportionality
(see hint below)
pressure, volume / directly proportional
or
inversely proportional
volume, temperature / directly proportional
or
inversely proportional
volume, number of gas particles / directly proportional
or
inversely proportional

Hint: A pair of variables is directly proportional when they vary in the same way (one increases and the other also increases). A pair of variables is inversely proportional when they vary in opposite ways (one increases and the other decreases).

Does the size of the particle matter when looking at the properties of gases? ______

11.  Compare the 4 cases and observations about pressure below.

The Comparisons
Starting condition / Hotter
particles / Particles in
smaller box / More,
hotter particles
Low Temperature / High Temperature / Low Temperature / High Temperature
Regular size box / Regular size box / Half size box / Regular size box
The Observations
LOW
PRESSURE / MEDIUM
PRESSURE / MEDIUM
PRESSURE / VERY HIGH PRESSURE
Use the simulation to develop a General Explanation for how air particles apply pressure that can explain the differences in the cases above. Write your explanation here:
Use your general explanation to explain observations for each case: