Experiment 2: Gas Laws

Experiment 2 Gas Laws GRADING RUBRIC EXPERIMENT 2 – LAB REPORT Worksheet (80 pts) Student name: ____ TA name: _ Day & time of the lab: __2/8/22 9AM _________________________ 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. IN- Lab Notebook Pages P. Sotelo 2022 1 2 3 4 DATA ANALYSIS PART A: Pressure–Volume Relationship of Gases (5 pts) Figure 1: 1. Use Excel (.csv) or Logger Pro 3.14 (.qmbl) to open the file you saved/emailed yourself from Part A. 2. To generate a new graph that relates pressure and volume (and is of reasonable dimensions): a. Select “Insert” from the task bar in the top left, then select “Graph”. b. You can change the name, and corresponding data, of an axis by simply left-clicking on it and selecting the desired option from the drop-down menu. c. Ensure that the graph plots Volume on the x-axis and Pressure on the y-axis. 3. To add a trendline to the data: a. Click on the graph to ensure that it is selected, then select “Analyze” and “Curve Fit”. b. In the General Equation box, scroll down until the option for Inverse (A/x) is visible. Select Inverse, select “Try Fit”, then “OK”. c. Reposition the box of parameters within the figure area so that all of the data points are visible. 4. To add an appropriate title to the graph, right-click on the graph and select “Graph Options” (this is not the same as a caption). 5. While the graph is still displayed, select “Analyze” and “Interpolate” to reveal a vertical cursor. Complete Table 1 and add additional entries under volume as needed to match the range of values studied in the laboratory (use 5 sig. figs. for the pressure and the constant). Table 1: Pressure readings and calculated 𝒌𝑷𝒂𝒓𝒕 𝑨 values at each specified volume. Constant, 𝒌𝑷𝒂𝒓𝒕 𝑨 Volume, 𝑽 Pressure, 𝑷 kPa x mL (mL) (kPa) see DQ #2 5.8 182.16 1056.5 7.8 137.98 1076.2 9.8 112.69 1104.4 11.8 93.04 1097.9 13.8 79.35 1095.0 15.8 68.43 1081.2 17.8 19.8 60.62 1079.0 53.42 1057.7 6. Copy and paste the final version of the graph. Figure 1: here… 5 6 PART B: Pressure–Temperature Relationship of Gases 7. Use Excel or Logger Pro 3.14 to open the file you saved from Part B. 8. To correctly analyze and apply the data obtained in Part B, all temperatures must be converted to Kelvin (K) from degrees Celsius (°C). To convert to units of K, create a new data column: a. Select “Data” from the task bar in the top left, then select “New Calculated Column”. b. In the Name box, type “*Temperature”, in the Short Name box, type “Temp”, and in the Units box, type “K”. (Note: *Temperature is not a typo – Logger Pro will not allow “Temperature” for the name because it is already being used with the default settings.) c. In the Expression box, enter the correct formula for the conversion by first typing “273+”, then selecting “Temperature” from the Variables (Columns) menu. d. Click “Done” to create the new column. 9. Generate a single graph that relates pressure and temperature (in Kelvin): a. Select “Insert”, then “Graph”. b. Change the names of the axes to produce a graph with *Temperature (K) on the x-axis and Pressure (kPa) on the y-axis. 10. Add an appropriate trendline to the data: a. Click on the graph to ensure that it is selected, then select “Analyze” and “Linear Fit”. b. Reposition the box of parameters so that all of the data points are visible. 11. Add an appropriate title to the graph, right-click on the graph and select “Graph Options”. 12. While the graph is still displayed, select “Analyze” and “Interpolate” to reveal a vertical cursor. Use this cursor to pan over the data and determine the pressure at each listed temperature in Table 2 below (use 5 sig. figs. for the pressure and the constant). Table 2: Pressure readings and calculated 𝒌𝑷𝒂𝒓𝒕 𝑩 values at each specified temperature. Constant, 𝒌𝑷𝒂𝒓𝒕 𝑩 Temperature, 𝑻 Pressure, 𝑷 (kPa/K) (K) (kPa) See DQ 6 300 84.19 .28063 320 89.11 .27847 340 83.78 .24641 360 98.97 .27492 13. When you have finished, hide the vertical cursor by selecting “Analyze” and “Interpolate” again. 14. Copy and paste the final version of the graph into the R&D section of the report. (5 pts) Figure 2: here… 7 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 above. The relationship between pressure and volume is an inverse one, meaning as pressure increases, volume will decrease. This can be seen by the graph (figure 1) as when volume is increasing, the pressure is getting lower, indicating an inverse relationship. Additionally, an equation that can be used to describe this relationship is Boyle’s law : PV = k. 2. (4 pts) Calculate an average of the values of 𝒌𝑷𝒂𝒓𝒕 𝑨 from the table above. In this study, what are the appropriate units of 𝒌𝑷𝒂𝒓𝒕 𝑨 ? The average of the values in k part A from the table is 1081 kPa x mL. With that being said, the units of k part a is kpa x mL. 3. (6 pts) Using the equation from Discussion Question 1 and value of 𝒌𝑷𝒂𝒓𝒕 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. Using the equation from Discussion Question 1 and the value of Kpart A from Discussion Question 2, the expected pressure of the gaseous sample at a volume of 2.5 mL is 432.4 kPa. Additionally, the pressure for a volume at 40 mL using the value of k part A is 27.00 kPa. To find these values, Boyle’s law was used which has a written equation, PV = k, that states the products of P and K will equal k. Using that formula, to find the value of pressure at 2.5 mL with the average kPa value from DQ 2 the calculation would be P(2.5 mL) = 1081 kPa x mL , 8 to which 1081 is divided by 2.5 to get 432.4 kpartA. This same mathematical process is used for the calculation with 40 mL as the equation is 1081= x(40) to get 27.00 kPA. 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 pressures at a volume of 2.5 mL is 432.4 kPa while it is 216.2 kPa for 5 mL, this is a decrease by a factor of 2. Additionally, when comparing the pressures of a volume of 2.5 and 10 mL it decreases by a factor of 4 as the volume for 10 mL is 108.2 Between 2.5 and 40 mL the pressure decreases by a factor of 16 as the pressure is 27.03 kPa for 40 mL. These results do make sense because as volume increases, pressure decreases, meaning when comparing values to 2.5, the larger the volume gets, the factor pressure is going to decrease increases. Moreover, the factor pressure decreases is exponential, as it went from 2, to 4, to 16, which to a power of 2. Part B 5. (11 pts) Describe the relationship between the pressure and the temperature of a confined gaseous sample. What equation is used to best describe this relationship (answer in DQ 5a)? (Hint: There are two correct answers, but proceed with the one that lists 𝑷 in the numerator; DQ 5a) Use that equation and the values obtained from Step 13 of the Data Analysis to complete Table 2. The relationship between pressure and temperature of a confined gaseous sample is direct, meaning as temperature increases, pressure increases as well. An equation to describe this relationship is Charles’ Law, P/T = k. a. Below, write the general equation describing the relationship between pressure and temperature: The general equation describing the relationship between pressure and temperature is P/T = k. b. Below, write the specific equation (see the trendline) used to complete this part (with the exact values of m and b): The specific equation to describe the relationship between pressure and temperature is y = 0.2464x + 10.265 6. (4 pts) Using the answer from DQ 5a, calculate an average of the four values of 𝒌𝑷𝒂𝒓𝒕 𝑩 from the table above. In this study, what are the appropriate units of 𝒌𝑷𝒂𝒓𝒕 𝑩 ? The average of the 4 values of kpartb is .27010 kPa/K and units is kPa/K. 9 7. (6 pts) Using the equation from Discussion Question 5a and value of 𝒌𝑷𝒂𝒓𝒕 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. Using the equation from discussion question 5a and value from k part B the expected pressure of a gaseous sample at a temperature of -50 C is 60.23 kPa. The pressure at a temperature of 200 C is 127. 8 kPa. 8. (8 pts) Calculate these two new pressures using a second method (DQ 5b): 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? If not, describe one or more sources of error within the experiment that might account for any discrepancies. Using the second method, the expected pressures at -50 C and 200 C are 65.21 kPa and 126.8 kPa. These values are similar to the calculated pressures from question 7. POST- lab notebook pages 10 11