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PV Practice

PV Practice. How does this happen?. Units and Conversions. Conversions to know: 1 atm = _____ 1L = _____. Units to know: Pa = _____ N = _____. Conversions are on your formula sheet. Unit equivalence is not. Kinetic Theory and Gas Laws. AP2. Energy Review.

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PV Practice

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  1. PV Practice

  2. How does this happen?

  3. Units and Conversions • Conversions to know: • 1 atm = _____ • 1L = _____ • Units to know: • Pa = _____ • N = _____ • Conversions are on your formula sheet. • Unit equivalence is not.

  4. Kinetic Theory and Gas Laws AP2

  5. Energy Review • Internal Energy – total energy of the gas; directly related to temperature • Work – volume change • Heat – energy added to or removed from; independent of temperature

  6. The Periodic Table Atomic # = # of protons OR electrons • All of the elements on the periodic table are referred to in terms of their atomic mass. The symbol u is denoted as an atomic mass unit. 1 u = 1.66 x 10-27 kg Atomic Mass = Protons + Neutrons and Molar Mass (g/mol)

  7. The Mole • The word “mole” is derived from Latin to mean “heap” or “pile”. • It is basically a chemical counting unit. • Used to convert units at STP (standard temperature and pressure) • The number of particles in one mole of a substance is given by Avogadro’s Number: This is simply the number of THINGS (molecules) per mole.

  8. Standard Temperature 273K Standard Pressure 1 atm Standard Volume 22.4 L/mol These are useful to remember when dealing with gasses at STP. You should know these values. STP

  9. Mole Road Map

  10. Factors that effect a GAS • The quantity of a gas, n, in moles • The temperature of a gas, T, in Kelvin (Celsius degrees + 273) • The pressure of a gas, P, in pascals • The volume of a gas, V, in cubic meters

  11. Gas Law #1 – Boyles’ Law “The pressure of a gas is inverse related to the volume” • Moles and Temperature are constant

  12. Gas Law #2 – Charles’ Law “The volume of a gas is directly related to the temperature” • Pressure and Moles are constant

  13. Gas Law #3 – Gay-Lussac’s Law “The pressure of a gas is directly related to the temperature” • Moles and Volume are constant

  14. Gas Law #4 – Avogadro’s Law “The volume of a gas is directly related to the # of moles of a gas” • Pressure and Temperature are constant

  15. Gas Law #5 – The Combined Gas Law You basically take Boyle’s Charles’ and Gay-Lussac’s Law and combine them together. • Moles are constant

  16. Gas Law #6 – The IDEAL Gas Law • All factors contribute! In the previous examples, the constant, k, represented a specific factor(s) that were constant. That is NOT the case here, so we need a NEW constant. This is called, R, the universal gas constant.

  17. Example 1 • Pure helium gas is admitted into a leak proof cylinder containing a movable piston. The initial volume, pressure, and temperature of the gas are 15 L, 2.0 atm, and 27 °C. If the volume is decreased to 12 L and the pressure increased to 3.5 atm, find the final temperature of the gas. 420 K or 147 °C

  18. Example 2 • A helium party balloon, assumed to be a perfect sphere, has a radius of 18.0 cm. At room temperature, (20 C), its internal pressure is 1.05 atm. Find the number of moles of helium in the balloon and the mass of helium needed to inflate the balloon to these values. He  Molar mass = 4.003 g/mol 0.0244 m3 293 K 1.052 moles 1.05x105 Pa m =4.21 g

  19. The other ideal gas law • Also given in terms of the number of molecules in a volume of a gas. N = number of molecules (or particles)

  20. Why two equations? • Just different ways to express the same thing. • One macroscopic view and one microscopic view.

  21. Multiple Choice Practice

  22. Kinetic Theory • Particles within a gas are constantly moving. Constantly colliding. Therefore: • They have a velocity and a kinetic energy. • Not all particles move at the same speed, but on average we can determine the speed of particles within a substance. What can effect the motion of these particles?

  23. Macroscopic and Microscopic expressions RMS Velocity μ – molecular mass (mass of a molecule or particle) M – molar mass (g/mol) (or the mass of one mole of particles) Square root of the average velocity squared of the molecules

  24. Gas Laws Practice

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