Name____________________ Per:_____ Gas Law Concepts & Conversions Part I- Concepts & Conversions 1. Explain on a molecular level how the smell of popcorn (gases) cooking in a microwave can diffuse so that it is smelled in the entire room. 2. a. What is meant by the term “standard temperature and pressure” (a.k.a STP)? b. What are the numeric values & units associated with STP? c. What is meant by the term “constant”? (Example: the volume of the can remained “constant”) 3. What are the 3 different scales used to measure temperature & who uses each the different scales (primarily)? 4. What are the conversion factors between Celsius and Kelvin? 5. Convert each of the following Celsius temperatures to Kelvin temperatures (show work). a. 0. ºC b. 27 ºC c. -50. ºC d. -273 ºC 6. Why do all temperatures need to be converted from Celsius to Kelvin in order to use them in the gas law calculations? 7. “Absolute Zero” (0 Kelvin) is a theoretical temperature that is impossible to achieve. What would happen to molecules at this temperature & why is this so unlikely to attain? 8. What are the different pressure measurements that exist & their conversion factors related to each other? 9. Convert each of the following into the unit specified. (Use dimensional analysis & show work). a. 125 mm Hg to atm b. 3.20 atm to kPa c. 5.38 kPa to Torr d. 1 atm to Torr Activity- Feeling Under Pressure Purpose: This activity allows you to compare the pressure and volume of a sample of air. Part I: Answer the following questions: 1. What did you feel when you pushed the plunger down from 40 mL to 30 mL to 20 mL? 2. Are you able to push the plunger all the way to the bottom? Explain why or why not. 3. Does the amount of air inside the syringe change? Explain your thinking. Part II: Quantitative Data. (You will collect quantitative data as a class.) 1. Fill in the table with the results of the demonstration. 2. Convert the weight to pressure by dividing by the area to get pounds per square inch. The area is the radius of the syringe squared times . (Area = r2) Trial Volume 1 50 mL 2 40 mL 3 30 mL 4 20 mL 5 15 mL 6 10 mL Weight (lbs) Pressure (lbs/ in2) 3. Make a graph of pressure versus volume. Put pressure on the y axis and volume on the x axis. 4. Describe what happens to the pressure shown on the scale as the volume of the air decreases. 5. Use your graph to estimate the following: a) If the volume is reduced to 32 mL what will the pressure be? b) If the volume is reduced to 16 mL what will the pressure be? 6. Explain why the number of molecules in the syringe didn’t change, but the volume did. 7. Describe the relationship between pressure and volume. Making sense: Why is it so difficult to push the plunger in as the volume gets smaller?
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