6.3.2.3 Specific latent If a change of state happens: 1 Define specific latent heat. Plan and out an heat. investigation to find the The energy needed for a Draw heating and cooling graphs specific latent heat of fusion substance to change state is for a substance including a called latent heat. When a change of state. of water. change of state occurs, the Interpret a heating or cooling Investigate the heating energy supplied changes the graph to explain what is for water by heating some ice energy stored (internal happening at each stage of the in a beaker until the water energy), but not the graph. temperature. evaporates. Use temperature Explain why a of ice at 0 °C sensors/data loggers to The specific latent heat of a that is being heated does not record the temperature at substance is the amount of increase in temperature initially. fixed intervals, eg 30 energy required to change the state of one kilogram of Calculate the energy for a seconds. A graph can be the substance with no change of state, mass or specific plotted of temperature change in temperature: latent heat of a substance given against time. the other values. Instead of the above carry Students will be expected to out the Institute of Physics convert to SI units and use investigation from Episode standard form where required. energy, E, in joules , J 608-2: Evaluate the use of different mass, m, in kilograms, kg coolants used in fridges in terms specific latent heat, L, in of the specific latent heat of the joules per kilogram, J/kg coolant and the boiling point of the coolant. Specific latent heat of fusion change of state from solid – Research the use of coolants in to liquid. fridges. Specific latent heat of Define specific latent heat of vaporisation change of – fusion and vaporisation. state from liquid to vapour.
6.3.2.3 Specific latent heat. If a change of state happens: The energy needed for a substance to change state is called latent heat. When a change of state occurs, the energy supplied changes the energy stored (internal energy), but not the temperature. The specific latent heat of a substance is the amount of energy required to change the state of one kilogram of the substance with no change in temperature: energy, E, in joules , J mass, m, in kilograms, kg specific latent heat, L, in joules per kilogram, J/kg Specific latent heat of fusion – change of state from solid to liquid. Specific latent heat of vaporisation – change of state from liquid to vapour. 1 Define specific latent heat. Draw heating and cooling graphs for a substance including a change of state. Interpret a heating or cooling graph to explain what is happening at each stage of the graph. Explain why a of ice at 0 °C that is being heated does not increase in temperature initially. Calculate the energy for a change of state, mass or specific latent heat of a substance given the other values. Students will be expected to convert to SI units and use standard form where required. Evaluate the use of different coolants used in fridges in terms of the specific latent heat of the coolant and the boiling point of the coolant. Research the use of coolants in fridges. Define specific latent heat of fusion and vaporisation. Plan and out an investigation to find the specific latent heat of fusion of water. Investigate the heating for water by heating some ice in a beaker until the water evaporates. Use temperature sensors/data loggers to record the temperature at fixed intervals, eg 30 seconds. A graph can be plotted of temperature against time. Instead of the above carry out the Institute of Physics investigation from Episode 608-2:
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