1 / 19

Ideal Gas Law

Ideal Gas Law. Why bother with Gases? Properties of a Gas Animation P, V, T, n Ideal Gas Law Examples of Ideal Gas Law Ideal Gas Law - #molecules version. Temperature and Gases. Gas Simplest material phase – all kinetic energy.

irisa
Download Presentation

Ideal Gas Law

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. Ideal Gas Law • Why bother with Gases? • Properties of a Gas • Animation P, V, T, n • Ideal Gas Law • Examples of Ideal Gas Law • Ideal Gas Law - #molecules version

  2. Temperature and Gases • Gas • Simplest material phase – all kinetic energy. • Energy “reservoir” – convert disordered KE to useful mechanical work. • Properties of a Gas • Pressure • Volume • Temperature • Quantity • 4 Properties are interrelated • Animation • Ideal gas law

  3. Ideal Gas Animation • Gas/piston animation (Java animation) ……..…… • Gas/piston animation http://www.chem.ufl.edu/~itl/2045/MH_sims/ideal_nav.swf • Other animations http://www.mhhe.com/physsci/chemistry/animations/chang_7e_esp/gam2s2_6.swf

  4. Ideal Gas Observations • Observations of P, V, T, n • Pressure vs. Volume (Boyle’s Law) P proportional to 1/V • Volume vs. Temperature (Charle’s law) V proportional to T • Pressure vs. Temperature (Gay-Lussac’s Law) P proportional to T • Pressure and volume vs. quantity PV proportional to n

  5. Ideal Gas Law – Primary units • Ideal gas law combines Boyle’s, Charles, Gay-Lussac’s PV = nRT • P proportional 1/V • V proportional T • P proportional T • P proportional n • Units • P in pascals • V in m3 • T in K° (not C °) • n in moles • R = 8.314 J/mol-K • Definition of Mole n = mass/molecular mass (N2=28g/mol, O2= 32g/mol, etc.)

  6. Ideal Gas Law – Alternative units • Ideal gas law combines Boyle’s, Charles, Gay-Lussac’s PV = nRT • P in atmospheres • V in liters • T in K° • n in moles • R = .0821 L-atm/mol-K • Use either primary units or alternative units completely, don’t mix n’ match! • Use primary units for First Law (Ch 15) calculations.

  7. Celsius vs. Kelvin • Degree sizes same! • Kelvin = Celsius with zero shifted to absolute zero. • May use Celsius when only relative changes important. • Thermal Expansion • Specific and Latent Heat problems • Thermal Conduction • Must use Kelvin when absolute temperature important. • Ideal Gas Law • Kinetic Theory • Thermal Radiation • First and Second Law Thermodynamics Similar to Gauge vs. Absolute Pressure

  8. Example 13-10 - volume 1 mole at STP • STP = 0C (273K), 1 atm (101.3 kPa) • Primary units • Alternative units

  9. Example 13-11 - helium balloon • Volume of 18 cm radius sphere • Number of moles in alternative units (just being different) • Mass of Helium

  10. Example 13-12 - mass of air in room • Volume of 5 x 3 x 2.5 m room • Number of moles • Mass of Air @ 29 g/mol (N2 28 g/mol, O2 32 g/mol)

  11. Example 13-13 – automobile tire An automobile tire is filled to a gauge pressure of 200 kPa at 10°C. After a long drive the temperature as risen to 40°. What is the pressure now? • Strategy – Put all constant quantities on same side of Ideal Gas Law • Convert 200 kPa gauge pressure to 301 kPa absolute pressure • Solve Convert 333 kPa absolute pressure back to 232 kPa gauge pressure

  12. More examples of ideal gas • Problem 29 V2 = V1 (P1/P2) (T2/T1) • Problem 30 T2 = T1 (P2/P1) (V2/V1) • Problem 31 ρ = 32 x 10-3/22.4 x 10-3 • Problem 32 P2 = P1 (n2/n1) • Problem 33 • Problem 36 n2 = n1 (P2/P1) • Problem 39 P2 = P1 (V1/V2)(T2/T1)

  13. Problem 29 – V change with P, T • First move all constant quantities to one side • Then solve for V2 Note: Arbitrary units OK, since only ratios important

  14. Problem 30 – T change with P, V • Move all constant quantities to one side • Solve for T2 (Diesel car) Note: Arbitrary units OK, since only ratios important

  15. Problem 31 – Density of O2 • Volume of 1 mole at STP 22.4 L = 0.0224 m3 (shown earlier) • Mass of a mole O2 32 g = .032 kg (lookup in table) • Density

  16. Problem 32 – Gas substitution • Calculate mole ratio for equal mass CO2 and N2 (since mass equal) • Move all constant quantities to one side • Solve for P2

  17. Problem 36 – Gas substitution • First find #moles O2 • Move all constant quantities to one side • Solve for n2 670 moles • Then find mass 670 moles Helium

  18. Problem 39 – P change with V, T • Move all constant quantities to one side • Solve for V2 Note: Arbitrary units OK, since only ratios important

  19. Ideal Gas Law - #molecules version • Ideal Gas Law can also be written: PV = NkTPV = nRT • N = nNA (N number of molecules) • k= R/NA (NA Avagadro’s number) • P in Pascals (no alternative units) • V in m3 • T in K° • Boltzman’s constant • k = R/NA = 1.38e-12 J/K

More Related