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CHEMISTRY

Air is heating up!. CHEMISTRY. Name: _______________________ Group #: _____________________ Year and Section: ______________ Teacher: Miss Cristina P. Sarmiento. A Learner-Centered Learning Environment Module on Gases. 1.

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CHEMISTRY

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  1. Air is heating up! CHEMISTRY Name: _______________________ Group #: _____________________ Year and Section: ______________ Teacher: Miss Cristina P. Sarmiento A Learner-Centered Learning Environment Module on Gases

  2. 1 Imagine that you are a mountain climber. You pause for a moment to appreciate the magnificent view beneath Mt. Palay-Palay (Pico de Loro) in Ternate Cavite. You also use the opportunity to catch your breath because the air becomes thinner or less dense at high altitudes. What does a mountain climber need to know about gases in order to enjoy climbing without danger?

  3. 2 Which of the following would be your response? Encircle one response . If you have other responses in mind. Write them inside the circle labeled “other response”. When temperature increases the gas pressure increases The air / gases on top of a mountainhas high density Behavior of Gases Gases fill their containers Gases have mass Gas particles are in constant random motion Other response

  4. WORKSHEET #1Name:________________________________________ Year & Section Decide which behavior of gases you would choose and state 3 reasons why you would choose those behavior. Write your reasons on the right. 3 Reasons My choice is… ________________________________________________________________________________________________________________________________________________________________________________ Other response: __________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

  5. To find out which among your responses is most effective, let’s try ACTIVITIES A and B. 4 Floating Bubbles or Sinking Bubbles To make air (floating) bubbles, use soap solution and an O ring. To make CO2 (sinking) bubbles, set up the apparatus in the laboratory. Add vinegar to the baking soda. Dip the end of the tubing in the dish of soap solution. Compare the behavior of the bubbles. Explain your observations based on your study of gases. Be ready to discuss your answers with the class afterwards. Observation and Comparison

  6. 6 5 GUIDE QUESTIONS ACTIVITY A: 1. How can you make a very large soap bubble ? ___________________________________________________________________________________________________ 2. What evidence suggests that gas particles are in constant motion? ___________________________________________________________________________________________________ 3. After performing the activities, which among the properties is incorrect. Why? ___________________________________________________________________________________________________ Now get a partner and compare your responses. Afterwards, answer the following: 1. Did both of you choose the same behavior of gases? ____________________________________________________________ 2. After knowing the behavior of gases your partner chose, do you feel confident about your own response? Why or why not? __________________________________________________________________________________________ 3. What can we do to find out which among these behaviors is true? __________________________________________________________________________________________

  7. To find out which among your responses is true, let’s try this ACTIVITY B. 7 • Hot Air Balloon • MATERIALS:dry cleaner plastic film bags (select a bag with the thinnest possible plastic and have several on hand. You may have to experiment with bags of different thickness), several small paper clips,cellophane tape, heat source (blow dryer, camp stove, etc.), matches, three feet of aluminum heat duct (if using open flame heat source), electric drill (to put holes in the heat duct) • PROCEDURE:1. Seal any openings and tears in the upper end of the bag with a minimum of cellophane tape.2. Attach several paper clips to the plastic around the lower opening. The number of paper clips to attach is determined by experimentation.3 Turn on the blow dryer (or light stove and then set the heat duct over it) • 4. Spread the bag opening wide to capture the rising hot air while supporting the upper end with your hand. It is best to have assistance in keeping the bag open so that it does not melt.5. When the bag is inflated with hot air, test its buoyancy by letting it go for a moment. If it rises quickly, stand back and let it fly otherwise continue heating it for a little longer.6. If the bag tips over and spills its hot air before it reaches the ceiling, add a few more paper clips to weigh down the bottom slightly. If the bag does not rise at all, remove a few clips.

  8. 9 8 GUIDE QUESTIONS ACTIVITY B: 1. Based on your observation, which one is less dense, hot or cold air? __________________________________________________________________ 2. What factor accelerates the motion of air molecules? __________________________________________________________________ 3. What happens to the plastic bag when placed over the heat source? Explain. ___________________________________________________________________________________________________ 4. After performing the activity, was the plastic bag successfully lifted? Why? ___________________________________________________________________________________________________ Now get a partner and share your observation and why your plastic bag was successfully lifted and the others’ were NOT.

  9. http://www.chemistry.ohio-state.edu/betha/nealGasLaw/ ( a website on gas tutorials) 10 In studying the behavior and properties of gases, scientists were able to formulate the different gas laws. http://www.chemtutor.com/gases.htm (A website about the different Gas laws and their formulas)

  10. 11 • Write the formulas of the different Gas Laws based on your reading from Web site 1. Fill in the concept map below. GAS LAWS Ideal gas law Graham’s law Boyle’s law Charles' law Dalton’s law Having completed the concept map, what can you say about the Gas Laws? ______________________________________________________________________________________________________________________________________

  11. 12 After completing the concept map of gas laws, let us now compare the formulas and differentiate the Laws by filling up the table below. You may go back to the websites if you need to. Be ready to share your work with a partner.

  12. This time, we will investigate the relationship of pressure of a gas with its temperature. Let’s try ACTIVITY C. 13 Materials: 2 identical tin cans with cover, 2 iron stands with rings, 2 burners, 2 thermometers. Procedure: Fill the two identical cans about ¼ full of water. Place the cover with inserted thermometer on one of the tin cans. Clamp the thermometer and submerge its bulb in the other tin can which is uncovered. Heat the cans separately to boiling. Measure the temperature in each set-up. Write your observation in each set -up

  13. 15 GUIDE QUESTIONS ACTIVITY C 14 1. Describe the effect of temperature on the pressure of gases? __________________________________________________________________ _________________________________ 2. What is the effect on the boiling temperature if the tin can is tightly covered? __________________________________________________________________ _________________________________ 3. Can you think of other examples in your house that apply this same principle? ___________________________________________________________________________________________________ Now get a partner and try to share your observation about pressure – temperature relationship.

  14. 16 What are principles involved in the following household technologies? Let us now apply the relationship of pressure of a gas with the temperature using examples from common household items. LPG (Liquefied Petroleum Gas). Why do you think it is advisable to place gas tanks away from direct heat? _______________________________________________________________________________________________________________________________________ Pressure Cooker. What will happen if the pressure cooker builds up to 61 torr in excess of atmospheric pressure? _________________________________________________________________________________________________________________________________________________________ Insecticide Sprays. Why do aerosol cans explode when heated? _______________________________________________________________________________________________________________________________________________________________

  15. Problem on Gas Law ... 17 Show your solution A. The volume of gas is 10 liters when its pressure is one atmosphere. How much pressure must be applied to reduce its volume to 5 liters at the same temperature?

  16. Problem on Gas Law ... 18 Show your solution The volume of a gas sample at 10 degree Celsius is 2 liters at a pressure P. At what temperature in degree Celsius should the gas be to increase its volume to 4 liters at the same pressure P?

  17. Website A: Practice Test 1 http://library.thinkquest.org/C006669/data/Chem/quizzes/gases.html Website B: Practice Test 2 http://library.thinkquest.org/17658/learn/gasesquiz.html Try answering Practice Tests 1 and 2. Count your correct answers and verify which item you got wrongto find out how you fared and how well prepared you are for the next thing to be done. Remember, be honest! You can only proceed to the next task if you scored at least halfof the items you need to answer.

  18. Performance Reflections ... • Read the Rubrics on the next slide. • Rate yourself by checking which of the categories (vertical column) you think you excelled per criteria (horizontal column) during activity. • Place your score on the right side column under Peer-Rating. • Be reminded that your teacher had rated you during your lab activity and your self rating will be compared to hers.

  19. Rubrics for LCLE Module on Gas Activity and Problem SolvingName: _______________________ Evaluator’s Name: _______________________

  20. THANK YOU!

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