(d) Ideal gas molecules

5.15 explain how molecules in a gas have random motion and that they exert a force and hence a pressure on the walls of a container

Gas laws:

  • Gas molecules have rapid and random motion.
  • When they hit the walls of the container, they exert a force.
  • Pressure = Force/Area

5.20 Explain, for a fixed amount of gas, the qualitative relationship between: pressure and volume at constant temperature, pressure and Kelvin temperature at constant volume.

  • As you heat the gas, the kinetic energy of the particles increases, and thus so does their average speed.
  • This means more collisions per second with the walls, and they exert a larger force on the wall.
  • This causes in the total pressure being exerted by the particles to rise.
  • If temperature is constant, the average speed of the particles is constant.
  • If the same number of particles is placed in a container of smaller volume they will hit the walls of the container more often.
  • More collisions per second means that the particles are exerting a larger force on the wall over the same time, so average force exerted on the walls has increased.

5.21 use the relationship between the pressure and Kelvin temperature of a fixed mass of gas at constant volume:

P1/T1 = P2/T2

*Temperature must be in Kelvin

Temperature law:

For a fixed mass of gas at constant volume, the pressure is directly proportional to the Kelvin temperature

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Section 1: Principles of chemistry

      a) States of matter

      b) Atoms

      c) Atomic structure

     d) Relative formula masses and molar volumes of gases

     e) Chemical formulae and chemical equations

     f) Ionic compounds

     g) Covalent substances

     h) Metallic crystals

     i) Electrolysis

 Section 2: Chemistry of the elements

     a) The Periodic Table

     b) Group 1 elements: lithium, sodium and potassium

     c) Group 7 elements: chlorine, bromine and iodine

     d) Oxygen and oxides

     e) Hydrogen and water

     f) Reactivity series

     g) Tests for ions and gases

Section 3: Organic chemistry

     a) Introduction

     b) Alkanes

     c) Alkenes

     d) Ethanol

Section 4: Physical chemistry

     a) Acids, alkalis and salts

     b) Energetics

     c) Rates of reaction

     d) Equilibria

Section 5: Chemistry in industry

     a) Extraction and uses of metals

     b) Crude oil

     c) Synthetic polymers

     d) The industrial manufacture of chemicals

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