E2_gas_laws_worksheet_SP2024

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Feb 20, 2024

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Experiment 2 Gas Laws EXPERIMENT 2 – LAB REPORT Worksheet (80 pts) Student name: Deena Bader TA name: Chikaodili Chukwuneke Day & time of the lab: Mondays 1-5 pm The lab report packet for this experiment should consist of the following in THIS ORDER: The lab report packet for this experiment should consist of the following: 1. (10 pts) IN-lab notebook pages 1.1. Experimental procedure 1.2. Observations that were noted and exact data file name (as saved from the LabQuest) 2. (70 pts) The WORKSHEET 2.1. (65 pts) Complete (full sentence) answers to ALL the discussion questions (DQ) and Data Analysis Section. 2.2. (5 pts ) POST-lab notebook pages 2.2.1. All calculations performed present Complete this worksheet and turn in your digital lab packet to Canvas. Feel free to adjust space in this document as needed. The tables provided here are only an example of these may look like, feel free to replace the entire tables with your own creations using Excel, etc All tables and figures (graphs) must be accompanied by captions which should be positioned above tables and below figures. TURN IN the digital copy to Canvas on the due date by 11:59 pm. All electronic material must be completed by the due date to avoid late penalties. 1 P. Sotelo SP2024
IN-LAB NOTEBOOK PAGES (10 pts) Name, date, title of experiment, detailed procedure, observations and data taken while in lab. Upload scans or images of your written in-lab notebook pages here. 2 P. Sotelo SP2024
DATA ANALYSIS For all calculations in this worksheet report the pressure and k values to 4 significant digits. 3 P. Sotelo SP2024
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See the lab manual post lab data analysis section for specific instructions on how to create the figures and get the data for the discussion questions. (5 pts/ea.) Copy and paste the two figures you created for Part A and Part B below. Make sure they have all the necessary components of a properly formatted figure. (See the document on canvas titled Report composition tips). Figure 1: here… Figure 1: The scatter plot graphs the relationship between a gas's volume (mL) and its pressure (kPa) found using a plastic syringe connected to a gas pressure sensor and LabQuest device. Figure 2: here… 4 P. Sotelo SP2024
Figure 2: The scatter plot graphs the relationship between the temperature (K) and the pressure (kPa) of a gas found by submerging a sealed Erlenmeyer flask and a temperature probe connected to a gas pressure sensor and LabQuest device in a boiling water bath. DISCUSSION QUESTIONS (Answer the following questions in full sentences .) Part A 1. (8 pts) Describe the relationship between the pressure and the volume of a confined gaseous sample. What equation is used to best describe this relationship? Use that equation and the values obtained from Step 5 of the Data Analysis to complete Table 1 below. The pressure and volume of a confined gaseous sample have an inversely proportional relationship. This correlation is most closely related to Boyle’s Law, which is: pV = k. This equation explains how when the volume of a confined gaseous sample is increased, the pressure of the sample decreases and vice versa. If one variable increases, the other must decrease in order to keep k constant. Table 1 : Pressure readings and calculated k Part A values at each specified volume. Volume, V (mL) Pressure, P (kPa) Constant, k Part A ( kPa * mL) 5.8 185.2 1,074 7.8 138.0 1,076 5 P. Sotelo SP2024
9.8 110.2 1,080. 11.8 91.51 1,079 13.8 78.17 1,079 15.8 68.34 1,080. 17.8 60.27 1,073 19.8 54.30 1,075 2. (4 pts) Calculate an average of the values of k Part A from the table above. In this study, what are the appropriate units of k Part A ? The average k value from part A can be calculated by adding all the k values and dividing by the number of values. The average of the values of k Part A is 1,077 kPa * mL. The appropriate units of k Part A is kPa * mL since the pressure of the gaseous sample was measured is kPa and the volume in mL and the two variables are multiplied to calculate k. Therefore, the units for k are kPa * mL. 3. (4 pts) Using the equation from Discussion Question 1 and value of k Part A from Discussion Question 2, calculate the expected pressure of the gaseous sample at a volume of 2.5 mL. Calculate the pressure at a volume of 40 mL. The expected pressure of the gaseous sample at a volume of 2.5 mL can be calculated by using Boyle’s Law and isolating pressure by dividing the average value of k, 1,077 kPa * mL, by the volume of 2.5 mL. The pressure of the gaseous sample is expected to be 430.8 kPa when it has a volume of 2.5 mL. Using the same process, the pressure of the gaseous sample is expected to be 26.93 kPa when it has a volume of 40 mL. 4. (8 pts) Compare the pressures at volumes of 2.5 and 5 mL. Compare the pressures at 2.5 and 10 mL. Compare the pressures at 2.5 and 40 mL. For each comparison, what is the numerical factor by which each variable increases or decreases? Do these results make sense? The expected pressure of the gaseous sample with a volume of 5 mL is 215.4 kPa compared to an expected pressure of 430.8 kPa at 2.5 mL. The numerical factor in which the pressure increased is 2. This makes sense because the volume of the sample doubled, meaning the pressure should decrease by a numerical factor of 2 to keep k constant. The expected pressure of the gaseous sample with a volume of 10 mL is 107.7 kPa compared to an expected pressure of 430.8 kPa at 2.5 mL. Because the volume increased by a factor of 4, the pressure also decreased by a factor of 4. The expected pressure of the gaseous sample with a volume of 40 mL is 26.93 kPa compared to an expected pressure of 430.8 kPa at 2.5 mL. Since the volume increased by a factor of 16, the pressure of the gaseous sample decreased by a factor of 16, too. With each comparison, the volume and pressure increase and decrease respectively by the same factor. Again, this pattern makes sense because the two variables have an inversely proportional relationship and will increase or decrease by the same factor. 6 P. Sotelo SP2024
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5. (4 pts) Compare your average k Part A to the slope of your trendline in Figure 1 . Describe in detail one or more sources of experimental error from this part of the lab. The slope of the trendline in Figure 1 is 1076.7, and the calculated average k value is 1077. When comparing these values, they are very close to each other, meaning the experimental and expected values are almost the same. This indicates a small experimental error, possibly when the volume of the syringe was being manipulated. My lab partner mentioned how keeping the plunger in place was difficult when measuring the pressure with smaller volumes, so the preciseness of the volumes may have influenced the pressure data collected and, therefore, the slope of the line. Part B 6. (9 pts) Describe the relationship between the pressure and the temperature of a confined gaseous sample. What is the general equation that can be used to best describe this relationship? Use that equation and the values obtained from Step 14 of the Data Analysis to complete Table 2 . What is the experiment specific equation (see the trendline) that can be used to describe this relationship (with the exact values of m and b)? Pressure and temperature have a directly proportional relationship; as the temperature of a confined gaseous sample increases, the gas pressure will also increase. In addition, if the temperature of the confined gaseous sample decreases, so too does the pressure of the gas. The general equation that can be utilized to describe this relationship best is Gay-Lussac’s Law, which is: P T = k. The law explains that if temperature increases, pressure must increase to keep k constant. The experiment specific equation, obtained from the trendline in Figure 2, that can be used to describe the relationship is y = 0.2749x + 8.5505. Table 2 : Pressure readings and calculated k Part B values at each specified temperature. Temperature, T (K) Pressure, P (kPa) Constant, k Part B ( kPa/K ) 300 82.92 0.2764 320 87.88 0.2746 340 92.84 0.2731 360 97.79 0.2716 7. (4 pts) Using the table from DQ 5 , calculate an average of the four values of k Part B from the table above. In this study, what are the appropriate units of k Part B ? The average of the four k Part B values is 0.2739 kPa/K. This number is calculated by adding the four k Part B values and dividing by 4. In this study, the appropriate units for k Part B is kPa/K because pressure was measured in kPa and temperature was measured in kelvin. Since the two variables are divided to calculate k Part B , the units for k Part B is kPa/K. 7 P. Sotelo SP2024
8. (6 pts) Using the general equation from DQ 5 , and value of k Part B from Discussion Question 6, calculate the expected pressure of the gaseous sample at a temperature of –50 °C. Calculate the pressure at a temperature of 200 °C. The expected pressure of the gaseous sample at a temperature of –50 °C is 61.08 kPa. This pressure is calculated by using Gay Lussac’s Law, P T = k. Pressure is isolated by multiplying average k Part B value, 0.2739, by 223 K which is -50 °C in Kelvin. This same calculation is applied to calculate the expected pressure of the gaseous sample at a temperature of 200 °C (473 K), which is approximately 129.5 kPa. 9. (8 pts) Calculate these two new pressures using the specific equation found in DQ 5 (the equation for the trendline on the Part B graph). What are the expected pressures at –50 °C and 200 °C using this method? Are they similar to the calculated pressures from Discussion Question 7? Describe in detail one or more sources of experimental error within the experiment that might account for any discrepancies. The expected pressure at –50 °C using the equation for the trendline on the Part B graph is 63.83 kPa. Using the same equation, the expected pressure at 200 °C (473 K) is approximately 125.8 kPa. These values are calculated by converting each temperature to kelvin and then substituting each one into the trendline equation: y = 0.2749x + 8.5505. These values are somewhat similar to the calculated pressures from discussion question 7 but not very precise. Some possible sources of experimental error include the rapid cooling of the water bath, causing the temperature probe readings being inaccurate at given temperatures and therefore pressures resulting in imprecise k values. (5 pts) POST-LAB NOTEBOOK PAGES For the post lab notebook pages, you must show a sample calculation of each unique calculation completed during the data analysis and discussion questions. 8 P. Sotelo SP2024
9 P. Sotelo SP2024
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