Boyles Law Pressure-Volume Relationship in Gases Experiment 6

C h r o me b oo t s Experiment \ SO ( ?> Boyle’s Law: Pressure-Volume Relationship in Gases 6 The primary objective of this experiment is to determine the relationship between the pressure and volume of a confined gas. The gas we use will be air, and it will be confined in a syringe connected to a Gas Pressure Sensor (see Figure 1 ). When the volume of the syringe is changed by moving the piston, a change occurs in the pressure exerted by the confined gas. This pressure change will be monitored using a Gas Pressure Sensor. It is assumed that temperature will be constant throughout the experiment. Pressure and volume data pairs will be collected during this experiment and then analyzed. From the data and graph, you should be able to determine what kind of mathematical relationship exists between the pressure and volume of the confined gas. Historically, this relationship was first established by Robert Boyle in 1662 and has since been known as Boyle’s law. OBJECTIVES In this experiment, you will • Use a Gas Pressure Sensor. and a gas syringe to measure the pressure of an air sample at several different volumes relationship between pressure and volume of the gas. • Determine therelationship between gas pressure and volume in a mathematical equation. the Describe • pressure at other volumes. the predict results to the Use • X7 J Figure 1 MATERIALS Computer (Chromebook ) Vernier GoILink Vernier Graphical Analysis app Vernier Gas Pressure Sensor 20 mL gas syringe PROCEDURE 1 . Prepare the Gas Pressure Sensor and an air sample for data collection. a. Connect the Vernier GoILink to the Vernier Gas Pressure Sensor. Connect to Chromebook via USB. b. With the 20 mL syringe disconnected from the Gas Pressure Sensor, move the piston of the syringe until the front edge of the inside black ring (indicated by the arrow in Figure 2) is positioned at the 10.0 mL mark. c. Attach the 20 mL syringe to the valve of the Gas Pressure Sensor. Chemistry with 6-1 Experiment 6 2. Prepare the computer for data collection by opening the Vernier Graphical Analysis app on your Chromebook. If the connections are correct, the y-axis will read “Pressure ( kPa) and the x-axis will read “Time (s)”. 3. To obtain the best data possible, you will need to correct the volume readings from the syringe. Look at the syringe; its scale reports its own internal volume. However, that volume is not the total volume of trapped air in your system since there is a little bit of space inside V. the pressure sensor. $ k To account for the extra volume in the system, you will need to adqOJJ mb p your syringe readings. For example, with a 5.0 mL syringe volume, the total volume'Wbt d be 5.8 mL. It is this total volume that you will need for the analysis. 4. Collect the pressure vs. volume data. It is best for one person to take care of the gas syringe and for another to operate the computer. a. Click COLLECT and move the piston to position the front edge of the inside black ring (see Figure 2) at the 5.0 mL line on the syringe. Hold the piston firmly in this position until the pressure value stabilizes. s Figure 2 b. When the pressure reading has stabilized, click STOP. (The person holding the syringe can relax after STOP is clicked.) Record the total gas volume ( in this case, 5.8 mL ) in your data table. Remember, you are adding 0.8 mL to the volume of the syringe for the total volume. Look at your graph to see where the pressure stabilized. Click anywhere on that section, and the pressure value will pop up. Record that pressure in kPa in your data table. c. Click COLLECT and move the piston to the 7J) mL line. When the pressure reading has stabilized, click STOP and record the total volume, 7.8 mL and the pressure measured in your data table. d. Continue this procedure for syringe volumes of 9 T), 11.0, 13.0, 15.0, 17.0, and 19.0 mL. 5. In your data table,(record the pressure and volume data airs displayed in the table (or, if directed by your instructor, print a copy of the tabl5}7” " 6. Examine the graph of pressure vs. volume. Based on this graph, decide what kind of mathematical relationship you think exists between these two variables, direct or inverse. To see if you made the right choice: P vs V V wd . DATA AND CALCULATIONS &o \ <& - Constant k . { P / M QifP V ) ] Pressure (KPa) Volume (mL) S.Q? U 33L It Mr 11 33 M. Z H0 3 \ s. e !*> $ \o°n I 'Mi " . < *1.1> 6 U. S°| ^ lO l* 0 n . fe 65 PROCESSING THE DATA io *n -^ 0 1 . Using your graph and data table, what happens to the pressure when the volume is doubled Hint: What is the pressure when the volume is 5.0 mL? What is the pressure when the volume is 10.0 mL? What is the relationship? \J ts Ml l S .lULPov Ofi .Cfo \dfa 2. Using the same technique as in Question 1, what does your data show happens to the pressure if the volume is halved from 20.0 mL to 10.0 mL? Show the pressure values in your answer. V is V\ e v f ( s dtoubUd 20. o vwL. ~ ( 0 , 0 tvxL ' ^ 11 ° 3. Using the same technique as in Question 1 , what does your data show happens to the pressure if the volume is tripled from 5.0 mL to 15.0 mL? Show the pressure values in your answer. \J -W led. f » /*, ( ef *. * O Wit iS . OrvvL s bD WPA. 4. From your answers to the first three questions and the shape of the curve in the plot of pressure vs. volume, do you think the relationship between the pressure and volume of a confined gas is direct qrfinverse;! Explain your answer. ^ ^ - ^ - ^ - -- ^ ' ~ As Vt Pa, 5. Based on your data, what would you expect the pressure to be if the volume of the syringe was increased to 40.0 mL? Explain or show work to support your answer. \J y, 4 7 P *[ . - = -^ / XI 10.0 ML 4o O 6. Based on your data, what would you expect the pressure to be if the volume of the syringe ^ HO FPa _ was decreased to 2.5 mL? Explain or show work to support your answer. \jJ Ib. o vwu - ^ no - ^ AAO k-Ptx 7. What experimental factors are assumed to be constant in this experiment? % & of pArticles Chemistry with Computers ^ p A ^ 6-3 Experiment 6 8. One way to determine if a relationship is inverse or direct is trvfind-n proportinnnlilv constant, k , from the data. If this relationship is direct, k - P / V \.If it is inverse, k - AP Based on your answer to Question 4, choose one of these formulas ana calculate K ior tne seven ordered pairs in your data table (divide or multiply the P and V values). Show the answers in the third column of the Data and Calculations table. ^ 9. How constant were the values for k you obtained in Question 8? Good data may show some minor variation, but the values for k should be relatively constant. r> Ach t * nof bfrd { 10. Using P, V , and k , write an equation representing Boyle’s law. Write a verbal statement that correctly expresses Boyle’s law. \ \i - V * 6-4 Y- Chemistry with Computers