Topic: Ideal Gas Laws

5.01 use the following units: degree Celsius (°C), Kelvin (K), joule (J), kilogram (kg), kilogram/metre3 (kg/m3), metre (m), metre2 (m2), metre3 (m3), metre/second (m/s), metre/second2 (m/s2), newton (N) and pascal (Pa)

The units for:

temperature: degree Celsius (°C) or Kelvin (K)

Energy: Joule (J)

mass: Kilogram (kg)

density: kilogram/metre cubed (kg/m3)

distance: metre (m)

area: metre squared (m2)

volume: metre cubed (m3)

velocity: metre per second (m/s)

acceleration: metre per second squared (m/s2)

force: newton (N)

pressure: pascal (Pa)

5.05 know and use the relationship between pressure, force and area:

pressure (Pa) = force (N)/ area (m2

  • Pressure is defined as force per unit area.
  • One pascal (Pa) is equivalent to one N/m2

5.10 describe the arrangement and motion of particles in solids, liquids and gases


  • Tightly packed
  • Held in fixed pattern
  • Vibrate about fixed positions


  • Tightly packed
  • Can slide over each other


  • Very spread out
  • Move with rapid, random motion


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

5.16 understand why there is an absolute zero of temperature which is –273 °C

Absolute zero:

  • At absolute zero the particles have no thermal energy or kinetic energy, so they cannot exert a force.
  • Absolute zero = 0 Kelvin = -2730C

5.17 describe the Kelvin scale of temperature and be able to convert between the Kelvin and Celsius scales

0 K = -273 0C

E.g.         100K = -1730C

                2000C = 473K

5.18 understand why an increase in temperature results in an increase in the average speed of gas molecules

As you increase the temperature of a gas, the kinetic energy of the gas particles increases and thus their average speed also increases.

5.19 know that the Kelvin temperature of a gas is proportional to the average kinetic energy of its molecules

The Kelvin temperature of a gas is proportional to the average kinetic energy of its molecules.

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

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

P1V1 = P2V2

Boyle’s law:

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

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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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