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Gases

Gases. http:// www.mhhe.com/physsci/chemistry/animations/chang_7e_esp/gam2s2_6.swf. Section 1 – The Gas Laws. 1. Use the kinetic-molecular theory to explain the behavior of gases. 2. State, apply, & calculate the 3 following gas laws:. a. Boyle’s Law. b. Charles’s Law.

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Gases

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  1. Gases http://www.mhhe.com/physsci/chemistry/animations/chang_7e_esp/gam2s2_6.swf

  2. Section 1 – The Gas Laws 1. Use the kinetic-molecular theory to explain the behavior of gases 2. State, apply, & calculate the 3 following gas laws: a. Boyle’s Law b. Charles’s Law c. Gay-Lussac’s Law

  3. A. The Kinetic-Molecular Theory 1. Gas particles do NOT attract or repel 2. Gas particles are small; virtually no volume 3. Gas particles are in constant, random motion 4. Kinetic energy is transferred during the elastic collisions • All gases have same averagekinetic energy at given temp

  4. B. The Nature of Gases 1. Actual gases do not always obey the kinetic-molecular theory 2. The KMT is based on 4 factors: a. Temperature (measured in Kelvin) [oC + 273 = K] b. Pressure (measured in atm, kPa, etc.) [1atm = 101.3kPa = 760 mmHg or torr] c. Volume (measured in liters or mL) d. Amount of Gas (measured in moles)

  5. http://www.chem.iastate.edu/group/Greenbowe/sections/projectfolder/flashfiles/gaslaw/boyles_law_graph.htmlhttp://www.chem.iastate.edu/group/Greenbowe/sections/projectfolder/flashfiles/gaslaw/boyles_law_graph.html C. Boyle’s Law 1. Temperature held CONSTANT 2. Found inverse relationship between pressure & volume 3. P1 V1 = P2 V2

  6. Volume –vs- Pressure of a Gas

  7. P1 V1 = P2 V2 Sample Problem 1:If the pressure of helium gas in a balloon has a volume of 4.0 L at 210 kPa, what will the pressure be at 2.5 L? 340 kPa Complete Practice Problems: #1 - #5 SHOW YOUR WORK!!!

  8. http://www.chem.iastate.edu/group/Greenbowe/sections/projectfolder/flashfiles/gaslaw/charles_law.htmlhttp://www.chem.iastate.edu/group/Greenbowe/sections/projectfolder/flashfiles/gaslaw/charles_law.html http://www.marymount.k12.ny.us/marynet/06stwbwrk/06gas/2slyscharles/2slysflash.html D. Charles’s Law 1. Pressure held CONSTANT 2. Found direct relationship between temperature & volume 3. V1 = V2 T1 T2 http://www.chem.iastate.edu/group/Greenbowe/sections/projectfolder/flashfiles/gaslaw/charles_law.html

  9. Temperature –vs- Volume of a Gas

  10. V1 = V2 T1 T2 Sample Problem 2:A gas sample at 40 oC occupies a volume of 2.32 L. If the temperature is increased to 75 oC, what will be the final volume? 2.58 L Complete Practice Problems: #6 - #8 SHOW YOUR WORK!!!

  11. http://www.marymount.k12.ny.us/marynet/06stwbwrk/06gas/1amcslussac/amcsgaylussac.htmlhttp://www.marymount.k12.ny.us/marynet/06stwbwrk/06gas/1amcslussac/amcsgaylussac.html E. Gay-Lussac’s Law 1. Volume held CONSTANT 2. Found direct relationship between temperature & pressure 3. P1 = P2 T1 T2 What would a graph look like for Gay-Lussac’s Law?

  12. P1 = P2 T1 T2 Sample Problem 3:The pressure of a gas in a tank is 3.2 atm at 22 oC. If the temperature rises to 60oC, what will be the pressure in the tank? 3.6 atm Complete Practice Problems: #9 - #11 SHOW YOUR WORK!!!

  13. Section 2 – The Combined Gas Law & Avogadro’s Principle 1. State, apply, & calculate the combined gas law 2. Relate number of particles and volumes using Avogadro’s Principle

  14. A. The Combined Gas Law 1. Amount of Gas held CONSTANT 2. P1 V1 = P2 V2 T1 T2 3. This law combines which 3 laws? http://kids.earth.nasa.gov/archive/air_pressure/balloon.html

  15. Sample Problem 4:A gas at 110 kPa and 30 oC fills a container at 2.0 L. If the temperature rises to 80oC and the pressure increases to 440 kPa, what is the new volume? 0.58 L Complete Practice Problems: #12 - #14 SHOW YOUR WORK!!!

  16. B. Avogadro’s Principle 1. Equal volumes of gases at the same temperature and pressure contains equal number of particles 2. Molar volume = 22.4 L/mol at STP 3. STP (Standard Temp & Pressure) Temperature = 0 oC or 273 K Pressure = 1 atm

  17. Sample Problem 5:Calculate the volume that 0.881 mol of a gas at STP will occupy. 19.7 L Complete Practice Problems: #15 - #17 SHOW YOUR WORK!!!

  18. Section 3 – The Ideal Gas Law 1. State, apply, & calculate the ideal gas law 2. State, apply, & calculate Dalton’s Law of Partial Pressure 3. State, apply, & calculate Graham’s Law of Effusion http://www.chemistry.ohio-state.edu/betha/nealGasLaw/fr2.1.html

  19. A. The Ideal Gas Law 1. Contains ALL variables 2. P V = n R T • WhereP = pressure (depends on R) V = volume (liters) n = amount of gas (moles) R = ideal gas constant (depends on pressure) T = temperature (Kelvin)

  20. R = ideal gas constant (depends on pressure)

  21. Sample Problem 6:Calculate the volume of a gas at STP with 2.80 moles. 62.8 L Sample Problem 7:Calculate the moles of a gas at STP with a volume of 238 L. 10.6 mol

  22. Sample Problem 8:Calculate the number of moles of gas contained in a 3.0 L vessel at 27 oC with a pressure of 1.50 atm. 0.18 mol Complete Practice Problems: #18 - #20 SHOW YOUR WORK!!!

  23. B. Dalton’s Law of Partial Pressure 1. Contains only pressure 2. Where pressure must be in the same units 3. Ptotal = P1 + P2 + P3 + . . .

  24. 4. Sample Problem 9:If the total pressure of a mixture of oxygen & nitrogen gases was 820 mmHg, how much pressure would nitrogen exert if oxygen had 580 mmHg? 240 mmHg Complete Practice Problems: #21 - #22 SHOW YOUR WORK!!!

  25. C. Graham’s Law of Effusion 1. Contains rates & masses of gases 2. Rate A = Mass B Rate B Mass A • WhereRate is measured in m/s Mass is measured in grams

  26. Sample Problem 8:If neon travels at 400. m/s, estimate the average speed of butane (C4H10) at the same temperature. 235 m/s Sample Problem 9:Chlorine has a velocity of 0.0380 m/s. What is the average velocity of sulfur dioxide under the same conditions? 0.0400 m/s

  27. Complete Practice Problems: #23 - #24 SHOW YOUR WORK!!!

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