GAS LAWS Boyle's Charles law ideal gas law
- 2. A. Kinetic Molecular Theory Particles in an ideal gas… • have no volume. • have elastic collisions. • are in constant, random, straight- line motion. • don’t attract or repel each other. • have an avg. KE directly related to Kelvin temperature.
- 3. C. Characteristics of Gases Gases expand to fill any container. • random motion, no attraction Gases are fluids (like liquids). • no attraction Gases have very low densities. • no volume = lots of empty space
- 4. C. Characteristics of Gases Gases can be compressed. • no volume = lots of empty space Gases undergo diffusion & effusion. • random motion
- 5. D. Temperature ºF ºC K -459 32 212 -273 0 100 0 273 373 32 F C 9 5 K = ºC + 273 Always use absolute temperature (Kelvin) when working with gases.
- 6. E. Pressure area force pressure Which shoes create the most pressure?
- 7. E. Pressure Barometer • measures atmospheric pressure Mercury Barometer Aneroid Barometer
- 8. E. Pressure Manometer • measures contained gas pressure U-tube Manometer Bourdon-tube gauge
- 9. E. Pressure 2 m N kPa KEY UNITS AT SEA LEVEL 101.325 kPa (kilopascal) 1 atm 760 mm Hg 760 torr 14.7 psi
- 10. F. STP Standard Temperature & Pressure 0°C 273 K 1 atm 101.325 kPa -OR- STP
- 12. A. Boyle’s Law P V PV = k Volume (mL) Pressure (torr) P·V (mL·torr) 10.0 760.0 7.60 x 103 20.0 379.6 7.59 x 103 30.0 253.2 7.60 x 103 40.0 191.0 7.64 x 103
- 13. A. Boyle’s Law The pressure and volume of a gas are inversely related • at constant mass & temp P V PV = k
- 14. k T V V T B. Charles’ Law Volume (mL) Temperature (K) V/T (mL/K) 40.0 273.2 0.146 44.0 298.2 0.148 47.7 323.2 0.148 51.3 348.2 0.147
- 15. k T V V T B. Charles’ Law The volume and absolute temperature (K) of a gas are directly related • at constant mass & pressure
- 16. k T P P T C. Gay-Lussac’s Law Temperature (K) Pressure (torr) P/T (torr/K) 248 691.6 2.79 273 760.0 2.78 298 828.4 2.78 373 1,041.2 2.79
- 17. k T P P T C. Gay-Lussac’s Law The pressure and absolute temperature (K) of a gas are directly related • at constant mass & volume
- 18. = k PV P T V T PV T D. Combined Gas Law P1V1 T1 = P2V2 T2 P1V1T2 = P2V2T1
- 19. GIVEN: V1 = 473 cm3 T1 = 36°C = 309K V2 = ? T2 = 94°C = 367K WORK: P1V1T2 = P2V2T1 E. Gas Law Problems A gas occupies 473 cm3 at 36°C. Find its volume at 94°C. CHARLES’ LAW T V (473 cm3)(367 K)=V2(309 K) V2 = 562 cm3
- 20. GIVEN: V1 = 100. mL P1 = 150. kPa V2 = ? P2 = 200. kPa WORK: P1V1T2 = P2V2T1 E. Gas Law Problems A gas occupies 100. mL at 150. kPa. Find its volume at 200. kPa. BOYLE’S LAW P V (150.kPa)(100.mL)=(200.kPa)V2 V2 = 75.0 mL
- 21. GIVEN: V1 = 7.84 cm3 P1 = 71.8 kPa T1 = 25°C = 298 K V2 = ? P2 = 101.325 kPa T2 = 273 K WORK: P1V1T2 = P2V2T1 (71.8 kPa)(7.84 cm3)(273 K) =(101.325 kPa) V2 (298 K) V2 = 5.09 cm3 E. Gas Law Problems A gas occupies 7.84 cm3 at 71.8 kPa & 25°C. Find its volume at STP. P T V COMBINED GAS LAW