Boyle’s Law Lab



All Chemistry Classes Boyle’s Law Lab Name __________________

Purpose: Students will investigate Boyle’s law using syringes, gas pressure sensors, and labquest digital data collection units. Students will then complete a formal lab report.

Background: Robert Boyle discovered the inverse relationship between pressure and volume in 1662. In class we demonstrated this relationship by using a vacuum pump which lowered pressure, causing a change in the volume of various objects (balloons, marshmallows, etc.) If we were to graph data from that demonstration, we’d put pressure on the x-axis as that was the variable that we changed. We’d put volume on the y-axis because that is what changed in response.

In this lab, we changed the volume of air in a syringe. Therefore, we’ll put volume on the x-axis and pressure on the y-axis.

Boyle’s law can be shown using the formula PoVo = PnVn or PV = k, where k stands for constant. These formulas assume that temperature is constant.

Getting started…

1. Gently plug the gas pressure sensor into the labquest unit

2. If the sensor isn’t working, click on sensors, sensor setup, channel 1, pressure, gas pressure sensor, OK, OK

3. If the sensor isn’t recording pressure in atm, click on sensors, change units, gas pressure sensor, atm

4. Using the attached stylus, click the “mode” – right side of screen, events with entry, choose Name and enter the word volume, choose units and enter mL, choose OK (lower right of screen)

Doing the experiment…. Set your syringe to 10.0 mL – then attach it gently to the gas pressure sensor

1. Click on the “Play” icon – lower left corner 2. Choose “Keep” – lower left corner

3. Enter value – 10.0 mL (the syringe measures to the “ones” place)

4. Choose “OK”

5. Then repeat the experiment for volume values of: 5.0, 8.0, 12.0, 15.0, 18.0, and 20.0 mL

6. Choose the “Stop” icon – lower left corner

7. Analyze 8. Curve fit 9. Check the Pressure box 10.Under “Fit Equation” – upper right of screen, choose “Power” 11. ok

12. Check out the box! It shows the equation and the constant (A) and the error. You will have to use the constant later in your lab report. Let’s see who can get the lowest error ( +/-)! Do the math with the constant: learn something new!

13. While students will attempt to e-mail their graphs and data, it may not work. Copy down the value for A in the box on the right of the graph!!! Copy down all volume and corresponding pressure values on a piece of paper!!! You can access these by clicking on the x/y icon on the top of the screen.

Lab requirements:

This will be a formal lab report presented in the following order. You need to have a:

1. Title

2. Purpose

3. Procedure (write “Refer to the handout for instructions on completing the laboratory exercise.”)

4. Materials (air, plastic syringe, gas pressure sensor and associated electronic equipment, labquest unit)

5. Data table – 3 columns P, V, 1/V (this last one needs to be calculated by students by taking the number 1 and dividing it by the volume in mL – make sure to pay attention to significant figures)

6. Graphs (P vs. V, and P vs. 1/V) – the first graph should be emailed. The second you’ll need to do yourself. If you cannot e-mail your graph the day of the lab, you’ll need to create graphs that are either hand-drawn on graph paper or use a computer program like Microsoft Excel (put pressure on the y-axis for both graphs).

7. Questions - listed below showing work when applicable.

8. Conclusion (a paragraph summarizing briefly what you did in the lab, what was observed, and what you learned – use appropriate vocabulary).

Questions: Complete on separate paper in the appropriate part of the body of your lab report.

1. Write the mathematical equation for Boyle’s law that you would use if: you had to solve for a new volume when given 2 pressure values and an old volume value.

2. Write the mathematical equation for Boyle’s law that you would use if: you had to solve for a new volume when given 1 pressure and the constant for the experiment.

3. Write the value for the constant for Boyle’s law that you obtained in the first part of the experiment (A= ).

4. By using the trend line on the graph only, estimate the pressure when the syringe holds 14.0 mL.

5. Repeat question 4 by using the Boyle’s law equation and the constant you obtained in the experiment to calculate the pressure when the volume is 14.0 mL.

6. By using the trend line on the graph only, estimate the volume when the pressure in the syringe is at 1.50 atm.

7. Repeat question 6 by using the Boyle’s law equation and the constant you obtained in the experiment.

8. What variable is assumed to stay constant in this experiment?

9. When would you expect to see greater error in your results for this experiment; when the volume is small or large? Explain why.

10. You were given the constant for the experiment by the computer program. Create a chart that shows the calculation of the constant at three different pressure/volume data points on your graph (use the pressure and volume values to calculate k (A). These answers will differ from the constant calculated by the program for the entire experiment.

This is incomplete – fix it – then add it next year

An extension of your knowledge – graphing 1/v vs. P

1. Click on the data table icon (x/y) 2. Click on table 3. New calculated column 4. Name 1/volume, then click Done 5. Unit 1/mL, then click Done

6. Equation type – choose A/X then click on column for x and choose 1/volume

7. Done 8. Insert 9. Graph

10. Now – on the graph, click on the bottom label to change to 1/v

11. On the graph, click on the left side and change to pressure

12. Analyze 13. Linear fit

14. Check out the box! Move the box so it doesn’t block anything important on the graph. Check out the slope, y intercept – hey this is the reason you take math class – to learn how to do science! Let’s go for the highest correlation. You don’t have to do anything with these numbers for the lab.

Let’s organize and print it…

1. Create a Microsoft word document

2. Put your partners full names on the top of it

3. Copy the data table (you have to highlight the data – you may have to manually label the titles of the columns) and graph(s) into it. MAKE SURE THAT YOU ALSO COPY THE SMALL “BOX” THAT APPEARS ON YOUR GRAPH. MAKE SURE THE BOX DOES NOT COVER IMPORTANT PARTS OF YOUR GRAPH. YOU WILL NEED THE DATA FROM THESE BOXES (SINCE YOU HAVE TWO GRAPHS)

4. Print the page

If…. You can’t copy, print, whatever – copy your data down on a piece of paper

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