Gas Laws - dimensional analysis, gas questions, 2 very easy graphs

Before starting the lab, complete the following problems. Return to lecture notes or homework if you don’t remember how to complete these.

Part A: Pressure vs. Volume

You will use the Gas Properties simulation on D2L to complete the following table.

· Click on the “Ideal” simulation (NOT explore, energy, or diffusion)

· Click on the green “+” sign to add particles of “air” to the container

· Use the double arrow to inject 200 Heavy (blue) particles (4 clicks)

· Do not change the number of particles in the simulation once you start collecting data

· Click the box next to the word “width”, this provides a scale that we will assume to be the volume of the container. (10.0 nm = 10.0 mL)

· Click the circle next to temperature to lock this variable.

· Click the handle on the container and drag left or right to adjust the volume of the container.

· The pressure will fluctuate, but do your best to choose the pressure reading that appears most frequently and record the pressure in the table for the following volumes: 5.0, 6.5, 8.0, 9.5, 11.0, 12.5, 14.0, and 15.0 mL.

Data Part A

Volume (mL)	Pressure (atm)	Constant, k
5.0	46.7	233.5
6.5	36.3	235.95
8.0	28.7	229.6
9.5	24.5	232.75
11.0	21.6	237.6
12.5	19.1	238.75
14.0	17.0	238
15.0	15.8	237

1. Calculate the constant, k, from your data and add it to the Data Table above with correct significant figures. (Hint: Is P/V or P•V for these data points constant?)

2. If the volume is doubled , what is the new pressure?

It goes down by half.

3. If the volume is halved, what is the new pressure?

It doubles.

[Insert Graphs 1 & 2 from Part A here. See Instructions.]

4. From your answers to the first two questions and the shape of the curve in the plot of pressure vs. volume, is the relationship between pressure and volume direct or inverse?

Inverse

5. Based on your data, what will the pressure be if the volume of the container was increased to 40.0 mL? Calculate using the equation for your best-fit line.

6. Based on your data, what will the pressure be if the volume of the container was changed to 3.0 mL? Calculate using the equation for your best-fit line.

7. What experimental factors are assumed to be constant in this experiment?

8. Generating a best fit line calculates the slope of the line that “best fits” the data. Any linear equation has the general form: y = m•x + b

This corresponds to:

Another way to calculate the slope is to calculate the k value for each data pair, which you did in #1 and added to the data table.

To quantify the variation of the k values, calculate the % range of the k values in the table according to the equation: (watch your significant figures!)

9. Write a verbal statement that correctly expresses the Boyle’s law equation written above.

Part B: Pressure vs. Temperature

You will use the same Gas Properties simulation on D2L to complete the following table.

· Click on the orange button with the circular arrow on the bottom right of the simulation to reset the simulation.

· Click on the green “+” sign to add particles of “air” to the container

· Use the double arrow to inject 200 Heavy (blue) particles (4 clicks)

· Do not change the number of particles in the simulation once you start collecting data

· Click the circle next to Volume to lock this variable.

· Find the thermometer at the top of the container, click the down arrow to change the units to °C.

· Find the bucket located under the container. Imagine the container is being submerged in the water bucket. Click the lever in the middle and pull down (you should see ice in the bucket) and pull up (you should see fire).

· Adjust the lever on the bucket to bring the temperature of the container to 0°C and record the corresponding pressure on the table.

· Adjust the lever to 3 different temperatures and record those pressure readings on the table. (Suggestions: use higher temperatures like room temperature and “hot water”)

Data Part B

Pressure (atm)	Temperature (°C)	Temperature (K)	Constant, k (P / T or P•T) (Use Kelvin values for T)
21.6	0	273
23.7	30	303
26.2	63	336
29.6	104	377

10. Calculate the constant, k, from your data and add it to the Data Table above with correct significant figures. (Hint: Is P/V or P•V for these data points constant?)

11. In order to perform this experiment, what two experimental factors were kept constant?

[Insert Graph 3 from Part B here. See Instructions.]

12. Based on the data and graph that you obtained for this experiment, is the relationship between gas pressure and temperature direct or inverse?

13. Predict what should happen to the pressure of a gas if the temperature is doubled.

14. Explain whether your prediction is supported by your data. Include specific data.

15. To quantify the variation of the k values, calculate the % range of the k values. Watch your significant figures!

16. Write the equation you used (above) to express the relationship between pressure and temperature (K). Use the symbols P, T, and k.

[Insert Graph 4 from Part B here. See Instructions.]

Since absolute zero is the temperature at which the pressure theoretically becomes equal to zero, the temperature where the regression line (the extension of the temperature-pressure curve) intercepts the y-axis should be the Temperature for absolute zero (in Celsius). The fit of your graph above should be linear, with an equation in the form y=m x +b, where b is the y-intercept.

17. What is the value of absolute zero? Show your work using your equation for the best-fit line.

Additional Questions:

Answer the following questions in the space provided.

18. Use the Kinetic Molecular Theory to explain the relationship of volume and pressure on the molecular level. Assume temperature and moles of gas are constant as they were in this experiment.

19. Use the Kinetic Molecular Theory to explain the relationship of temperature and pressure on the molecular level. Assume volume and moles of gas are constant as they were in this experiment.