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Do Now In Do Now section, answer:

Do Now In Do Now section, answer:. What do you think makes a hot air balloon fly? Why do you think your ears pop when you are in an airplane? Why is the upstairs of a home usually warmer than downstairs?. Understanding the Behavior of Gases 5 Keys Points. Gas molecules are spread far apart.

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Do Now In Do Now section, answer:

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  1. Do NowIn Do Now section, answer: What do you think makes a hot air balloon fly? Why do you think your ears pop when you are in an airplane? Why is the upstairs of a home usually warmer than downstairs?

  2. Understanding the Behavior of Gases5 Keys Points • Gas molecules are spread far apart. • Gas molecules move rapidly and spread out to fill the room (think room spray). • As a gas is heated, the molecules begin to move faster, causing the gas to expand (more space taken up-volume). • As the gas molecules hit the edge of their container, they create pressure. • The faster and more frequently gas molecules hit the edge of their container, the greater the pressure.

  3. Let’s revisit the Do Now and see if we can answer some of these questions. • Look over your answers to the Do Now. • Given what we just discussed regarding the behavior of gases, make any changes you would like to your answers. • Extra credit to those who do research and bring in the answers to those questions we didn’t already answer.

  4. Chick Demo • In your notes, record your observations. • Write down an explanation for why this happened.

  5. Marshmallow Syringe • What happens to the marshmallow as the syringe is pushed in? • What is happening to the pressure? The volume? • What happens to the marshmallow as the syringe is pulled out? • What is happening to the pressure? The volume?

  6. Boyle’s Law • Pressure and volume are inversely proportional: as pressure , volume as pressure , volume • Formula: P1V1 = P2V2, where 1 is initial and 2 is final • Pressure can have many units: • atm • Torr • mmHg • kPa • Pa

  7. Using Boyles’ Law P1V1=P2V2 Example 1: A sample of gas under a pressure of 822 kPa has a volume of 312 cm3. The pressure is increased to 948 kPa. What volume will the gas occupy at the new pressure? Step 1: Identify your P’s and V’s P1 = 822 kPa starting pressure V1 = 312 cm3starting volume P2 = 948 kPa ending pressure V2 = ?

  8. Using Boyle’s Law (cont.) Step 2: Plug and Chug P1V1=P2V2 (822 kPa)(312 cm3) = (948 kPa) V2 (822 kPa)(312 cm3) = V2 (948 kPa) 270.53 cm3 = V2

  9. Example 2 The volume of a gas is 204 cm3 when the pressure is 925 kPa. A change in pressure causes the volume of the sample to change to 306 cm3. What must the new pressure be? Step 1: Identify your P’s and V’s P1= 925 kPa V1= 204 cm3 P2= ? V2= 306 cm3 Step 2: Plug and Chug (925kPa)(204cm3) = P2 (306 cm3) (925 kPa)(204 cm3) = P2 (306 cm3) 617 kPa = P2 P1V1=P2V2

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