1 / 20

Properties of Gases

Properties of Gases. Gases. We use gases in our everyday live Fridges, fuel, deep sea diving (ok not everyday) Force due to gas is called pressure SI unit Pa = 1 Newton/metre 2 Atmospheric pressure is the amount of pressure exerted by air – at sea level about 101 kPa. Units. Pg. 149.

stacey
Download Presentation

Properties of Gases

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. Properties of Gases

  2. Gases • We use gases in our everyday live • Fridges, fuel, deep sea diving (ok not everyday) • Force due to gas is called pressure • SI unit Pa = 1 Newton/metre2 • Atmospheric pressure is the amount of pressure exerted by air – at sea level about 101 kPa.

  3. Units Pg. 149

  4. Relationship between Pressure and Volume • We can see that if we increase the volume the pressure decreases, and if we decrease the volume the pressure increases. • Pressure and volume have an inverse relationship • All other conditions are left the same, temperature, amount of substance

  5. Boyle’s Law P1V1 = P2V2 • As the pressure on a gas increases, the volume of the gas decreases proportionally, provided that the temperature and chemical amount of gas remain constant.

  6. Relationship between Temperature and Volume • Jacques Charles observed that there is a relationship between temperature and volume when doing experiments using hot air balloons. • Units of temperature (˚C) or kelvin (k). • Absolute zero is 0 k nothing can be colder.

  7. Cooling of a Gas

  8. Charles’ Law V1 / T1= V2/ T2 • As the temperature of a gas increases, the volumes increases proportionally, provided that the pressure and chemical amount of gas remain constant • This needs to be done in kelvin • T (K) = t (˚C) + 273

  9. Combined Gas Law • Boyle’s Law PV = constant • Charles’ Law V/T = constant • We are able to combine both to give P= constant

  10. Summary P1V1 = P2V2 • STP: 0 ˚ C and 101.325 kPa • SATP: 25 ˚ C and 100. kPa • 101.325 kPa = 1 atm = 760 mm Hg • T (K) = t (˚ C) + 273 V1 / T1= V2/ T2 P= constant

  11. Properties of Gases • Kinetic molecular theory explains a lot about the properties of gases • Gases are compressible - the distance between the molecules • Gas pressure – the amount of collisions that occur • Boyle’s Law • Charles’ Law

  12. Molecular motion

  13. Combining volumes • Law of combining gases • when measured at the same temperature and pressure, volumes of gaseous reactant and products of chemical reactions are always in simple ratios of whole numbers • Avogadro’s Theory • Equal volumes of gases at the same temperature and pressure contain equal numbers of molecules

  14. Example • H2 + Cl2 -> 2HCl • Since the ratio is 1:1:2 then if 1.0 L of hydrogen combined with 1.0 L of Chlorine it would give 2.0 L of hydrogen chloride. • These ratios hold true for coefficients, chemical amounts, and volumes

  15. Molar Volume of Gases • The volume that one mole occupies at a specified temperature and pressure • Combining the laws we have learnt previously • Given the symbol Vm • V = nVm OR n = V/Vm • The relationship of chemical amount (n), volume (V) and molar volume (Vm) • At STP one mole has a volume of 22.4 L • At SATP one mole has a volume of 24.8 L

  16. The Ideal Gas Law • Law based on how gases will interact within a system. • Hypothetically all gas follow this law • Need to make a few assumptions from the real world

  17. PG. 172

  18. Ideal Gas Law • If we recall Boyle’s Law • Charles’ Law • Avogadro’s theory • Can combine all these to give: • - constant • -universal gas constant

  19. Application • http://jersey.uoregon.edu/Piston/

  20. Partial Pressure • The pressure inside a closed container is maybe up of the pressure of each of the gases would have in the same volume contained within it. • P = P1 + P2 + P3 + … • Example: • H2(g)+ Cl2(g)-> 2HCl(g) • P = PH2 + PCl2 + PHCl

More Related