# Bell Ringer The gas with the largest volume at STP is: A.10.0 g He B.10.0 g Ne C.10.0 g Ar D.10.0 g Kr Source: 2004 VA Chemistry EOC Exam He:10.0 g He.

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Bell Ringer The gas with the largest volume at STP is: A.10.0 g He B.10.0 g Ne C.10.0 g Ar D.10.0 g Kr Source: 2004 VA Chemistry EOC Exam He:10.0 g He x 4.00 g He 1 mol He x 22.4 L He = 56.0 L He (56.0 L He)

Bell Ringer The gas with the largest volume at STP is: A.10.0 g He B.10.0 g Ne C.10.0 g Ar D.10.0 g Kr Source: 2004 VA Chemistry EOC Exam Ne:10.0 g Ne x 20.18 g Ne 1 mol Ne x 22.4 L Ne = 11.1 L Ne (56.0 L He) (11.1 L Ne)

Bell Ringer The gas with the largest volume at STP is: A.10.0 g He B.10.0 g Ne C.10.0 g Ar D.10.0 g Kr Source: 2004 VA Chemistry EOC Exam Ar:10.0 g Ar x 39.95 g Ar 1 mol Ar x 22.4 L Ar = 5.61 L Ar (56.0 L He) (11.1 L Ne) (5.61 L Ar)

Bell Ringer The gas with the largest volume at STP is: A.10.0 g He B.10.0 g Ne C.10.0 g Ar D.10.0 g Kr Source: 2004 VA Chemistry EOC Exam Kr:10.0 g Kr x 83.80 g Kr 1 mol Kr x 22.4 L Kr = 2.67 L Kr (56.0 L He) (11.1 L Ne) (5.61 L Ar) (2.67 L Kr)

GAS LAWS Ms. Besal 3/10/2006

Lesson Objectives You will be able to: Name and describe 5 characteristics of gases Identify three differences between ideal gases and real gases. Define the term “STP” List 4 units for pressure measurement Explain and describe the relationship between temperature and pressure of gases, according to Charles’ Law. Explain and describe the relationship between volume and pressure of gases, according to Boyle’s Law. Explain how temperature, pressure, and volume of gases are all related according to the combined gas law. Solve mathematic problems about Charles’ Law, Boyle’s Law, and the combined gas law.

What are Characteristics of a GAS?

: Gas Laws In the REAL WORLD: Gases are fat. (they have mass) Gases hog the sofa. (they have volume) Gases are pushy and have an attitude toward other gases. (they exert forces on each other) In an IDEAL WORLD: Gases are skinny. (they have no mass) Gases make themselves invisible. (they have no volume) Gases are not confrontational. (they do not interact… elastic collisions) Image Source: mtv.com

SO FAR… Standard Temperature & Pressure 273 K 1 atmosphere (atm)

What does PRESSURE mean? P A F = In Life: Pressure = a chemistry quiz every day In Science: Pressure = force per unit area

How else can we measure Pressure?

SO FAR… Standard Temperature & Pressure 273 K 1 atmosphere (atm)

How can we change Gases? ActionVariable Heat it up/Cool it downTemperature Compress or DecompressPressure Change container sizeVolume

How are Temperature and Volume Related? InitialFinal Temperature Volume T1T1 T2T2 V1V1 V2V2

Temperature Volume x x x x x x x How are Temperature and Volume Related? x x x x x x “At constant pressure… temperature and volume are directly proportional”

Charles’ Law “At constant pressure… temperature and volume are directly proportional.” V1V1 T1T1 V2V2 T2T2 = Temperature is always measured in Kelvin! 0ºC = 273 K

How can we change Gases? ActionVariable Heat it up/Cool it downTemperature Compress or DecompressPressure Change container sizeVolume

How are Volume and Pressure Related? InitialFinal Volume Pressure V1V1 V2V2 P1P1 P2P2

How are Volume and Pressure Related? Pressure Volume x x x x x x x x x x x x x “At constant temperature… volume and pressure are inversely proportional”

Boyle’s Law “At constant temperature… volume and pressure are inversely proportional.” V1V1 P1P1 V2V2 P2P2 = xx

To Recap… Charles’ Law: Relates Temperature and Volume. V1V1 P1P1 V2V2 P2P2 = xx V1V1 T1T1 V2V2 T2T2 = Boyle’s Law: Relates Pressure and Volume

…THEREFORE: Temperature, Volume, and Pressure are all related! = V1V1 T1T1 P1P1 V2V2 T2T2 P2P2

Practice 100.0 cm 3 oxygen at 10.50 kPa changes to 9.91 kPa. What is the new volume of the gas? 1. = V1V1 T1T1 P1P1 V2V2 T2T2 P2P2 =V1V1 P1P1 V2V2 P2P2 (100.0 cm 3 O 2 )x(10.50 kPa)=(9.91 kPa)(V 2 )x V2V2 =(100.0 cm 3 O 2 )x(10.50 kPa) (9.91 kPa) =106 cm 3 O 2 Boyle’s Law!

(150.0 mL SO 2 )(748 mmHg) (140.6 mL SO 2 ) P2P2 = = Practice 2.150.0 mL sulfur dioxide at 748 mmHg changes to a new volume of 140.6 mL. What is the new pressure of the gas? V1V1 T1T1 V2V2 T2T2 = P1P1 P2P2 V1V1 V2V2 =P1P1 P2P2 = 798 mmHg x(748 mmHg)(150.0 mL SO 2 )(P 2 )x(140.6 mL SO 2 )

Practice 75.0 cm 3 of hydrogen at 27.0ºC changed to –10.0ºC. What is the new volume of the gas? 3. = V1V1 T1T1 P1P1 V2V2 T2T2 P2P2 = 300 K 75.0 cm 3 H 2 = V2V2 263 K V2V2 =(263 K)x(75.0 cm 3 H 2 ) (300 K) =65.8 cm 3 H 2 Charles’ Law! V1V1 T1T1 V2V2 T2T2 Kelvin!

Practice A gas occupies a volume of 0.560 L. The original temperature was cooled to 7.71 ºC and the resulting volume was 0.400 L. What was the original temperature of the gas? 4. = V1V1 T1T1 P1P1 V2V2 T2T2 P2P2 = T1T1 =(280.71 K)x(0.560 L) (0.400 L) = 393 K T1T1 0.560 L0.400L 280.71 K 120.ºC

Practice 140. L chlorine at 15.0ºC and 110.0 kPa changed to 40.0ºC and 123.5 L. What is the new pressure? 5. = V1V1 T1T1 P1P1 V2V2 T2T2 P2P2 288 K (140 L Cl 2 ) = (123.5 L Cl 2 ) 313 K P2P2 =(140. L Cl 2 )(110.0 kPa) (288 K) = 136 kPa (110.0 kPa)(P 2 ) (313 K) (123.5 L Cl 2 )

V2V2 =(500.0 mL H 2 )(121 kPa) (293 K) (273 K) (101.3 kPa) Practice 500.0 mL of hydrogen at 20.0ºC and 121 kPa changed to STP. What is the new volume of the gas? 6. = V1V1 T1T1 P1P1 V2V2 T2T2 P2P2 = 293 K (500.0 mL H 2 )(120 kPa)(V 2 ) 273 K (101.3 kPa) = 556 mL H 2

For Next Class: Homework: Last page of Gas Laws Packet: Problems 1-10, 11-25 ODD QUIZ on Charles, Boyle, and Combined Gas Laws 24 points. 3 short answer/FITB problems (2 points each) 3 math problems (6 points each) 2 points for correct equation 2 points for correct math 2 points for correct labels

What Should I Study? how pressure, temperature, and volume relate to each other in Boyle’s, Charles’, and Combined Gas Laws. how to determine changing conditions using math (practice problems & homework). standard conditions of temperature and pressure; how to convert from Celsius to Kelvin, from kPa to atm to mm Hg. how real gases and ideal gases differ.

Lesson Objectives You should be able to: Name and describe 5 characteristics of gases Identify three differences between ideal gases and real gases. Define the term “STP” List 4 units for pressure measurement Explain and describe the relationship between temperature and pressure of gases, according to Charles’ Law. Explain and describe the relationship between volume and pressure of gases, according to Boyle’s Law. Explain how temperature, pressure, and volume of gases are all related according to the combined gas law. Solve mathematic problems about Charles’ Law, Boyle’s Law, and the combined gas law.

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