1. Chapter 11 GASES 기체의 성질

2. Challenger

3. Gas 기체의 상태 (state of the gas) –Volume –Temperature –Pressure –Amount

4. Pressure Force = (mass of an object) x (acceleration) = (change of the momentum) Pressure for gases are the molecules colliding with the walls of the container

5. Pressure Unit 1 기압, 1 atm, atmosphere – 지구 해수면 높이에 작용하는 대기압력 수은 (Hg) 기둥 높이 – 토르, torr, mmHg –1 atm = 760 torr Pa, pascal –1 Pa = N/m 2 –1 atm = 101300 Pa –pound per sq inch

6. Gases 기체 부피는 기체 분자의 수 ( 몰수 ) 에 비례

7. Gases 기체 부피는 온도에 비례 –absolute temperature scale (K) –hot air balloon –Charles’s Law

8. Gases 기체 부피와 압력은 반비례 –Boyle

9. Gases three equations that govern gases equations can be combined in to one equation

10. Perfect Gas Equation 적당한 비례상수 R, gas constant equation can be rearranged, Perfect Gas Equation

11. Perfect Gas Assumptions – 기체는 끊임없이 random motion 을 하는 분자로 이루어져 있다 – 기체 분자의 크기는 무시할 수 있다 – 기체 분자 사이에는 인력이나 반발력이 없다 – 기체 분자들은 완전 탄성 충돌을 한다

12. Gas Constant Standard Conditions Pressure – 1 atmosphere Moles – 1.00 mole Temperature – 0  C = 273 K Volume – 22.4L

13. Gas Problems All four variables are needed to completely solve problems or define a gas –volume, pressure, temperature, moles Changes in one variable can be solved, if the other variables are constant –Ideal Gas Equation can be simplified

14. Gas Problems Change in volume if the temperature changes, with pressure and moles constant Now an equation with only V and T can be set-up

15. Gas Problems Ideal Gas Equation can be used to set-up any number of equations or relationships

16. Density of Gases Why do some “float” and some “sink”? –1937, Hindenberg –H 2 vs. He Density change –mass/volume –different mass –different volume

17. Air bag 48 km/hour car collision –no protection : 5000N for 20 cm 2 –with sea belts : 5000N for 200 cm 2 –with air bag : 5000N for 2000 cm 2 SUPPLEMENTAL RESTRAINT SYSTEM!

18. Gases in Solution Gases are soluble in water Does solubility of gas increase or decease? – 온도와 압력 열오염, Thermal Pollution –raising the normal water temperature decreases the solubility of gases in the water – 물의 온도가 10 도에서 30 도로 올라가면 용해산소의 1/3 이 기화된다

19. Homework 교과서 354 쪽 연습문제 –1, 4, 9 교과서 예제 11.4, 11.5, 11.6 마감 1/11( 금 ) 수업 시작 전까지 기말시험 1/17 목요일 – 범위 7 장 이후 –1/16 수요일은 study day

20. References http://www.lemurzone.com/airbag/airbags.h tm