14

• 14.1 Use a simple kinetic theory model to explain the different states

  of matter (solids, liquids and gases) in terms of the movement

  and arrangement of particles - solid

  .They have a fixed shape and cannot flow because the particles cannot move from place to place

  .They cannot be compressed or squashed because the particles are close together and have no space to move into
• 14.1 Use a simple kinetic theory model to explain the different states

  of matter (solids, liquids and gases) in terms of the movement

  and arrangement of particles - gas

  .They flow and completely fill their container because the particles can move quickly in all directions

  .They can be compressed or squashed because the particles are far apart and have space to move into
• 14.3 Core Practical: Investigate the densities of solid and liquids

  1)Place the object on a digital balance and note down its mass

  2)Use either the ruler, Vernier callipers or micrometre to measure the object's dimensions (width, height, length, radius) - the apparatus will depend on the size of the object

  3)Repeat these measurements and take an average of these readings before calculating the density
• 14.4 Explain the differences in density between the different states of

  matter in terms of the arrangements of the atoms or molecules

  Most substances are the most dense when they are in solid form and the least dense when they are in a gaseous form. This is due to the arrangement of the molecules; with solids' molecules being closer together and gases being far apart.
• 14.5 Describe that when substances melt, freeze, evaporate, boil,

  condense or sublimate mass is...

  conserved and that these physical changes differ from some chemical changes because the material recovers its original properties if the change is reversed
• 14.6 Explain how heating a system will..

  change the energy stored within the system and raise its temperature or produce changes of state
• 14.7 Define the terms specific heat capacity and specific latent heat

  and explain the differences between them

  Specific Heat Capacity - The amount of energy needed to raise the temperature of 1 kg of substance by 1°C.

  Specific Latent Heat - The amount of energy needed to melt or vaporise 1 kg at its melting or boiling point.
• 14.10 Explain ways of reducing unwanted energy transfer through

  thermal insulation

  Energy loss through windows can be reduced using double glazing. These kind of windows have air or a vacuum between the two panes of glass. Air is a poor conductor, while a vacuum can only transfer energy by radiation. Energy loss through walls can be reduced using cavity wall insulation
• 14.11 Core Practical: Investigate the properties of water by

  determining the specific heat capacity of water

  1)Place the beaker on the digital balance and press 'tare'

  2)Add approximately 250 ml of water and record the mass of the water

  3)Place the immersion heater and thermometer in the water

  4)Connect up the circuit as shown in the diagram, with the ammeter in series with the power supply and immersion heater, and the voltmeter in parallel with immersion heater

  5)Record the initial temperature of the water at time 0 s

  6)Turn on the power supply, set at approximately 10 V, and start the stopwatch

  7)Record the voltage and current

  8)Continue to record the temperature, voltage and current every 60 seconds for 10 minutes
• 14.11 Core Practical: Investigate the properties of water by obtaining a

  temperature-time graph for melting ice

  1)Place some ice in a beaker so it is about half-full

  2)Place a thermometer in the beaker

  3)Place the beaker on a tripod and gauze and slowly start to heat it using a bunsen burner

  4)As the beaker is heated, take regular temperature measurements (e.g. at one minute intervals)

  5)Continue this whilst the substance changes state (from solid to liquid)

  6)The results can then be plotted on a graph
• 14.12 Explain the pressure of a gas in terms of the motion of its

  particles

  The particles move in random directions. When they collide with the walls of a container they exert a force which acts at a right angle to the container. This causes pressure.
• 14.13 Explain the effect of changing the temperature of a gas on the

  velocity of its particles and hence on the pressure produced by a

  fixed mass of gas at constant volume (qualitative only)

  As the temperature of the gas increases, the particles gain kinetic energy and their speed increases. This means that the particles hit off the sides more often and with greater force.
• 14.14 Describe the term absolute zero,

  Absolute zero is defined as: The temperature at which the molecules in a substance have zero kinetic energy

  (-273 °C)
• 14.15 Convert between the kelvin and Celsius scales

  The formula to convert Kelvin into Celsius is

  C = K - 273.15

  All that is needed to convert Kelvin to Celsius is one simple step: Take your Kelvin temperature and subtract 273.15. Your answer will be in Celsius.
• conversion between units in physics

  .Giga (G) = 10^9

  .Mega (M) = 10^6

  .Kilo (k) = 10^3

  .Deci (d) = 10^-1

  .Centi (c) = 10^-2

  .Milli (m) = 10^-3

  .Micro (μ) = 10^-6

  .Nano (n) = 10^-9

  .Pico (p) = 10^-12

  .Femto (f) = 10^-15
• 14.6 Explain how heating a system will..

  change the energy stored within the system and raise its temperature or produce changes of state
• 14.6 Explain how heating a system will..

  .change the energy stored

  within the system and raise its temperature or produce changes

  of state