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Properties of Gases
Properties of Gases and Gas Laws
| Question | Answer |
|---|---|
| Definition of a gas | A gas is a substance that has no fixed shape or volume and diffuses to fill any container in which it is placed. |
| Temperature used when measuring gases | Kelvin |
| Brownian Motion | Random movement of particles in a gas |
| Pressure of a gas (definition) | The pressure of a gas is the force it exerts per unit area. |
| Units used to measure the pressure of a gas | N/m>2 or the pascal |
| Atmospheric pressure in Pascals | 1x10>5 or 100,000Pa or 100kPa |
| Units for measuring the volume of a gas | metres cubed |
| How to convert cm cubed into meters cubed | divide by 1,000,000 |
| STP | At STP 1 mole of ANY gas will occupy 22.4L |
| Measurements for STP | Standard Temperature: 273K, 0 celcius. Standard Pressure: 1x10>5Pa/100kPa/1atm |
| Boyle's Law | Boyle's Law states that at a constant temperature the volume of a fixed mass of gas is inversely proportional to its pressure. |
| Relationship between Pressure and 1/Volume | Directly proportional |
| Mathematical conclusion from Boyle's Law | pressure x volume = k |
| Charles Law | Charles' Law states that at a constant pressure the volume of a fixed mass of gas is directly proportional to its temperature on the Kelvin scale |
| Mathematical conclusion from Charles' Law | Volume/Temperature = k |
| Guy Lussacs' Law of Combining VOlumes | Gases react in small whole number ratios provided that their volumes are measured at the same temperature and pressure |
| Avogadro's Law | This states that equal volumes of gases contain equal numbers of molecules, under the same temperature and pressure |
| 4 rules of Kinetic Gas Theory | 1: Particles of a gas are in continuous random motion. 2: There is no attractive or repulsive forces between these molecules 3: There is no difference between the volume of a gas and the container it is in. 4: The collisions are perfectly elastic. |
| Ideal Gas | An ideal gas is a gas that obeys all the assumptions of kinetic theory and all the gas laws at every temperature and pressure. |
| Real Gases behave like Ideal Gases when: | Low pressure as the molecules are far apart. High temperature as the molecules are moving rapidly. |
| Real Gases differ from Ideal gases when: | High pressure as the molecules are pushed close together. Low temperature as they begin to condense into liquids Most gases do exhibit some form of attractive of repulsive forces |
| Ideal Gas Equation | Pv=nRT |
| Volume of gases in the ideal gas equation | meters cubed |
| Universal Gas Constant | 8.31 |