Gas Laws Learning Assignment

Gas Laws How are the variables that describe a gas related? Why? Imagine buying a balloon bouquet at a party store. How will the helium gas in the bouquet behave if you carry it outside on a hot summer day? How will it behave if you carry it outside during a snowstorm? What happens if the balloons are made of latex, which can stretch? What happens if the balloons are made of Mylar®, which cannot stretch? What if you add just a small amount of gas to each balloon? What if you add a lot of gas? In this activity, you will explore four variables that quantify gases—pressure (P), volume (V), temperature (T), and moles (n) of gas. These four variables can be related mathematically so that predictions about gas behavior can be made. 1. In Model 1, what does a dot represent? internal pressure 2. Name two materials that the containers in Model 1 could be made from that would ensure that they were “nonflexible?” steel aand glass 3. In Model 1, the length of the arrows represents the average kinetic energy (think average speed) of the molecules in that sample. Which gas variable (Pinternal, V, T or n) is most closely related to the length of the arrows in Model 1? 200k 4. Complete the following table for the two experiments in Model 1. Experiment A Independent Variable Dependent Variable Controlled Variable(s) volume temp amount of gas Experiment B gas volume temp 5. Of the variables that were controlled in both Experiment A and Experiment B in Model 1, one requires a nonflexible container. Name this variable, and explain why a nonflexible container is necessary. In your answer, consider the external and internal pressure data given in Model 1. Read This! Pressure is caused by molecules hitting the sides of a container or other objects. The pressure changes when the molecules change how often or how hard they hit. A nonflexible container is needed if the gas sample is going to have an internal pressure that is different from the external pressure. If a flexible container is used, the internal pressure and external pressure will always be the same because they are both pushing on the sides of the container equally. If either the internal or external pressure changes, the flexible container walls will adjust in size until the pressures are equal again. 6. Name the two factors related to molecular movement that influence the pressure of a gas. temp amont of gas 7. Provide a molecular-level explanation for the increase in pressure observed among the flasks of Experiment A. adding more gas increase the collison with the wall 8. Provide a molecular-level explanation for the increase in pressure observed among the flasks of Experiment B. incresse of temp causes the gas to move faster and clide more 9. Predict what would happen to the volume and internal pressure in Experiment A of Model 1 if a flexible container were used. volume would increase 10. Predict what would happen to the volume and internal pressure in Experiment B of Model 1 if a flexible container were used. presure would increase 11. For each experiment in Model 1, determine the relationship between the independent and dependent variables. A direct proportional relationship means both variables increase (or decrease) together. An inverse proportional relationship means as one variable increases, the other decreases and vise versa. Write an algebraic expression for the relationship using variables that relate to the experiment (Pinternal, V, T or n). Use k as a proportionality constant in each equation. Experiment A is completed for you. Experiment A Direct or Inverse Proportion? Algebraic Expression Experiment B Direct inverse Pinternal = kn pinternal=K/V Model 2 – Gases in a Flexible Container 12. Consider the gas samples in Model 2. a. Name two materials that the containers in Model 2 could be made from that would ensure that they were “flexible”? RUBBER plastic b. What is always true for the external and internal pressures of a gas in a flexible container? external and internal pressure are equal 13. Complete the following table for the three experiments in Model 2. Experiment C Independent Variable Dependent Variable Controlled Variable(s) temp Experiment D voulme pressure pressure volume temp Experiment E temp volume pressure 14. Provide a molecular level explanation for the increase in volume among the balloons in Experi ment C. (How often and/or how hard are the molecules hitting the sides of the container?) as temp increases the gas moves faster 15. Provide a molecular level explanation for the increase in volume among the balloons in Experiment D. as volume incrases the gas has more room to move around 16. Provide a molecular level explanation for the increase in volume among the balloons in Experiment E. gas moves faster and colides with more force into the walls 17. Compare Experiment A of Model 1 with Experiment C of Model 2. How are these two experiments similar and how are they different in terms of variables? the are differnt bcause of the volume 18. Compare Experiment B of Model 1 with Experiment D of Model 2. How are these two experiments similar and how are they different in terms of variables? they look the same b1 just has more presure 19. If Experiment E of Model 2 were done in a nonflexible container, would there be any change to the internal pressure of the flask when the external pressure was reduced? Explain. 20. For each experiment in Model 2, determine the relationship between the independent and dependent variables, and write an algebraic expression for the relationship using variables that relate to those in the experiment (Pinternal, V, T or n). Use k as a proportionality constant in each equation. A direct proportional relationship means both variables increase (or decrease) together. An inverse proportional relationship means as one variable increases, the other decreases and vise versa. Use k as a proportionality constant in each equation. Experiment E is completed for you. Constant Pressure Experiment C Direct or Inverse Proportion? direct Algebraic Expression Experiment D inverse Experiment E Inverse V=k v=k*t 1 𝑃𝑖𝑛𝑡𝑒𝑟𝑛𝑎𝑙 21. The three samples of identical gas molecules below all have the same internal pressure. Rank the samples from lowest temperature to highest temperature, and add arrows of appropriate size to illustrate the average kinetic energy of the molecules in the samples. The longer the arrows, the faster the particles would be moving.