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KINETIC THEORY OF GASES Th e kinetic theory of gases proposes that: 1 Gases consist of molecules (small particles) that are in continual random motion. 2 The actual volume of all the molecules present in a sample of gas is negligible compared to the total volume they occupy.
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KINETIC THEORY OF GASES The kinetic theory of gases proposes that: 1Gases consist of molecules (small particles) that are in continual random motion. 2The actual volume of all the molecules present in a sample of gas is negligible compared to the total volume they occupy. 3Intermolecular forces are negligible. 4Pressure is due to collision of the particles with walls of the container. 5Temperature is a measure of the average kinetic energy (or speed) of the gas molecules.
AVOGADRO’S LAW Equal volumes of different gases, measured at the same temperature and pressure, contain the same number of molecules. 1 mol of gas at STP occupies 22.4L 1 mol of gas at NTP occupies 24.4L Ideal Gas Equation pV = nRT for all other conditions V = nRT/P
Avogadro’s law or Avogadro’s hypothesis, after Avogadro who proposed it in 1811. At constant temperature and pressure 70 mL of oxygen, O2, contains the same number of molecules as does 70 mL of nitrogen, N2, or 70 mL of ammonia, NH3. Since helium and argon are monatomic gases (the molecules are atoms,The number of particles in 70 mL of helium or argon is the same as the number of molecules in 70 mL of oxygen. Equal volumes of different gases, measured at the same temperature and pressure, contain the same number of moles. Measured at the same temperature and pressure, 1 mole of any gas has the same volume as 1 mole of any other gas.
Q1. If 10mL of methane gas burns completely in oxygen. What volume of oxygen, carbon dioxide and steam are produced? (Assume constant pressure and that temp > 100oC Typical questions Q2. 57mL of Xe originally at 273K and one atmosphere pressure (101325Pa) is heated to 390K and the pressure is reduced to 54000Pa. What volume will it occupy? http://webtools.gieskes.nl/pages/images/explosion.gif
BOYLE’S LAW For a certain amount of gas at a constant temperature, the volume is inversely proportional to its pressure. (As the pressure goes up the volume goes down) p 1/V p = k/V Copy this + Learn pV = k and for the same quantity of gas p1V1 = p2V2
http://www.antonine-education.co.uk/Physics_AS/Module_2/Topic_8/Boyle_1.gifhttp://www.antonine-education.co.uk/Physics_AS/Module_2/Topic_8/Boyle_1.gif
Q2. 250mL of Xenon at 2 atm pressure (A) is connected to an evacuated 500mL container B (vacuum). The tap opens and the gas rushes into B.Calculate the new pressure T B A
Q1. Flask A contains 400mL of nitrogen at 1 atm pressure. Flask B contains 100mL of oxygen at 4 atm. The tap opens and both gases mix. What will be the resulting pressure. (Assume the gases do not react) T B A
Flask A contains 100mL of Ar at 15atm pressure. This is connected to B and flask containing 1000mL of nitrogen at 57000Pa. Tap T opens and both gases combine. Find (a) the new pressure (these gases do not react) and (b) the total number of particles. T B A