1 / 21

The Empirical Gas Laws

The Empirical Gas Laws. Unit 10 Chapter 13. Boyle’s Law. Published in 1662 by Robert Boyle, it states that for a fixed amount of a gas at a fixed temperature, the pressure of the gas is inversely proportional to the volume of the gas. P ∝ V -1 Generalizing this, we get .

tatum
Download Presentation

The Empirical Gas Laws

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. The Empirical Gas Laws Unit 10 Chapter 13

  2. Boyle’s Law • Published in 1662 by Robert Boyle, it states that for a fixed amount of a gas at a fixed temperature, the pressure of the gas is inversely proportional to the volume of the gas. • P ∝ V-1 • Generalizing this, we get

  3. Boyle-ing your Brain • A gas occupies 17.4 liters at 0.862 atm. What is the pressure if the volume becomes 15.0 L? • P1 = 0.862 atm V1 = 17.4 L • P2 = ? V2 = 15.0 L • (0.862 atm)(17.4 L) = P2(15.0 L) • P2 = 1.000 atm

  4. Charles’s Law • Published in 1802 by Joseph Gay-Lussac based off of work from the 1780’s by Jacques Charles, it states that for a fixed amount of a gas at a fixed pressure, the volume of the gas is directly proportional to the temperature of the gas. • V ∝ T • Generalizing this, we get (since there is a sign inversion at 0 °C, always use Kelvin)

  5. Giving Your Brain a Charlie Horse • The temperature of a 4.00 L sample of gas is changed from 10.0 °C to 20.0 °C. What will the volume of this gas be at the new temperature? • V1 = 4.00 L T1 = 10.0°C + 273 = 283 K • V2 = ? T2 = 20.0°C + 273 = 293 K V2 = 4.14 L

  6. Pressure/Temperature Law • Published in 1702 by Guillaume Amontons but made famous by Gay-Lussac (in the same paper from 1802), it states that for a fixed amount of a gas at a fixed volume, the pressure of the gas is directly proportional to the temperature of the gas. • P ∝ T • Generalizing this, we get (remember to always use Kelvin)

  7. Feeling the Pressure • If a gas in a closed container is pressurized from 15.0 atm to 16.5 atm and its original temperature was 23.7 °C, what would the final temperature of the gas be? • P1 = 15.0 atm T1 = 296.7 K • P2 = 16.5 atm T2 = ? T2 = 326.4 K = 53.4°C

  8. The Combined Gas Law • Combining Boyle’s, Charles’s, and the Pressure/Temperature Law, assuming a fixed amount of gas, we get: (Always use Kelvin!)

  9. I’ll Have the Combo-Meal • A gas has a volume of 800.0 mL at -23.00 °C and 300.0 torr. What would the volume of the gas be if it were heated to 289.5 °C and the pressure doubled? • P1 = 300.0 torr V1 = 800.0 mL T1 = 250.00 K • P2 = 600.0 torr V2 = ? T2 = 562.5 K V2 = 900.0mL

  10. Avogadro’s Law • Published in 1811 by Amedeo Avogadro, it states that for a gas with a fixed pressure and temperature, the volume of the gas is directly proportional to the number of particles of the gas – we now use moles. • V ∝ n • Generalizing this, we get

  11. Attack of the Mole • A container with a volume of 18.7 L contains 0.379 mol nitrogen. • How many moles of fluorine must be added to increase the volume to 43.4 L? • V1 = 18.7 L n1 = 0.379 mol N2 • V2 = 43.4 L n2 = ? n2 = 0.880 mol nF2 = 0.880 – 0.379 = 0.501 mol F2

  12. Ideal Gas Law (pt 1) • Published in 1834 by Émile Clapeyron based off of Boyle’s Law and Charles’s Law, it states that for an ideal gas, the pressure-volume product is directly proportional to the mole-temperature product. • PV ∝ nT 

  13. Ideal Gas Law (pt 2) • The proportionality constant is the same for all gases! • It is called the Ideal (or Universal) Gas Constant with symbol R. • Adding R, we get

  14. What’s the Pirate Movie Rated? • R has many possible values. • The 3 most common ones: • If P is in atm, R = 0.08205746 atm·L / mol·K • in kPa, R = 8.314472 kPa·L / mol·K • in mmHg, R = 62.36367 mmHg·L / mol·K (same for torr)

  15. An Ideal Test • What volume will 1.15 moles of H2 occupy at 20.0ºC and 801.8 mmHg? • P = 801.8 mmHg V = ? • n = 1.15 mol T = 293.0 K P V = n R T • (801.8)V = (1.15)(62.36)(293.0) • V = 26.20628835 = 26.2 L

  16. Universally Yours • At what temperature will 10.967 g of oxygen occupy 0.683 L at 1,266.4 kPa? • P = 1,266.4 kPa V = 0.683 L • n = ? T = ? • n = 10.967 g O2 / 32.00 g/mol = 0.3427 mol O2 • P V = n R T • (1,266.4)(0.683) = (0.3427)(8.314)T • T = 303.5760326 = 303.6 K T = 30.6°C

  17. Ideal Gases Ideal gases are assumed to consist of: • 1. Randomly moving point particles (no size/volume) that are • 2. Infinitely compressible and • 3. Have no intermolecular attractions (i.e. will not stick to other atoms/molecules)

  18. But Seriously, Folks There is no such thing as an ideal gas! • 1. Real gases are not point particles. • They have a volume • And they are usually at least two atoms bonded together • (except the noble gases)

  19. Deviation from Ideal • 2. Real gases are not infinitely compressible and • 3. Individual molecules show at least a small amount of attraction to other molecules • This is how we are able to liquefy & solidify gases.

  20. Losing “R” Religion

  21. Approaching the Ideal • Gases exhibit ideal behavior at low pressures and high temperatures (big volumes). • The closest thing to an ideal gas is helium.

More Related