matter, in particular that the particles within the substance are not solid spheres and that the forces between the particles are not represented. model, use a tray, filled with ping-pong balls (or marbles), and shake it. You can vary the number of ping-pong balls to demonstrate the three states. 6.3.1.1. The particle model of matter to explain density of materials. The differences in density between the different states of matter to be explained in terms of the arrangements of the particles (atoms or molecules). 0.5 Explain why the different states of matter have different densities in of mass and volume of the material.. Draw diagrams to show the particle arrangement of solids, liquids and Use the diagrams to explain the differences in densities between solids, liquids and gases. Make models of solids, liquids and gases using plasticine. Does the model produced show the 3D structure of these states? Use the model of the tray filled with balls if you haven’t done it in The particle model of matter lesson. Evaluate the models used to explain the properties of solids, liquids and gases. How well do these models cope with water which is less dense than ice (solid water)? Cyberphysics – The Particle Theory – states of matter 6.3.1.2 Changing the state of a substance. When substances change state (melt, freeze, boil, evaporate, condense or sublimate), mass is conserved. 0.5 Why do substances change state? Why does the temperature of a substance remain constant when the substance is changing Explain how, when a substance changes the mass of the substance is unchanged as there is still the same number of atoms Find, by experiment, the melting point of salol. Compare value obtained with true value. Is there a discrepancy? How do you account for the discrepancy?
6.3.2.1 Internal energy of a system. Heating and temperature. Energy is stored inside a system by the particles (atoms and molecules) that make up the system. This is called internal energy. Internal energy is the total kinetic energy and potential energy of all the particles (atoms and molecules) that make up a system. Heating changes the energy stored within the system by increasing the energy of the particles that make up the system. And, either the temperature of the system increases, or changes of state happen. 1 What effect does increasing the temperature of an object have on the atoms that make up the object? Describe temperature a measure of the average kinetic energy of the particles in a substance. Describe and explain how increasing the temperature of a substance affects the internal energy of a substance. Define internal energy. Explain how the strength of the bonds between the particles will affect how much energy is needed to change the state of the substance. Evaluate data on the melting points and boiling points of different substances linked to the strength of the forces between the particles. Explain what is happening at each stage of the heating curve produced. Model the behaviour of atoms within a solid as it is heated past its melting point. You can use the tray of ping-pong balls or the kinetic theory apparatus if available. Critically analyse the model and suggest improvements to it. Investigate the heating curve 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. 6.3.2.2 Specific heat capacity. If the temperature of the system increases: the increase in temperature depends on the mass of the 1 Describe and explain how the amount of water in a kettle affects how quickly it boils. Plan a practical to investigate the rate of heating of various metals using a joulemeter to
substance heated, what the substance is and the energy input to the system. The following equation applies: change in thermal energy, ∆E, in joules, J mass, m, in kilograms, kg specific heat capacity, c, in joules per kilogram per degree Celsius, J/kg oC temperature change, ∆θ, in degrees Celsius, oC The specific heat capacity of a substance is the amount of energy required to the temperature of one kilogram of the substance by one degree Celsius. Explain why a pan of cooking oil heats up faster than a pan of water, with the same mass of each, in terms of specific heat capacity. Why is water used in central heating systems? Define specific heat capacity. Describe the factors that affect how quickly the temperature of a substance increases, eg why does a half-full kettle heat up faster than a full kettle of Calculate the change in thermal energy, mass, specific heat capacity or the temperature change of a substance that is heated or cooled. The equation will be provided on the equations sheet. Students should be able to convert to SI units and use standard form in their answers. Explain why special concrete blocks are used in storage heaters. determine the energy input. If no joulemeter is available, use an ammeter, I, a voltmeter, V, and heat the material for a fixed amount of time, t. Calculate the energy transferred, E, using: Determine the specific heat capacity of water by experiment.
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:
temperature, the greater the average kinetic energy and so the faster the average of the molecules. Describe and explain how the motion of molecules in a gas changes as the gas is heated. Why are gas cylinders likely to explode in a fire? use Institute of Physics’ Episode 601-1: 6.3.3.1 How gases exert forces on the walls of their containers. When the molecules collide with the wall of their container they exert a force on the wall. The total force exerted by all of the molecules inside the container on a unit area of the walls is the gas pressure. 0.5 Describe why gases exert a force on a container. Explain what is meant by gas pressure in terms of the forces exerted by the gas molecules on a given area. Explain how blowing up a balloon too much can cause it to pop in terms of gas pressure. Research how the gas pressure in a submarine it from crushing at depth. Use PhET interactive simulations to model gas pressure: 6.3.3.1 How changing the temperature of a gas affects the pressure exerted. Changing the temperature of a gas, held at constant volume, changes the pressure exerted by the gas (known as the Pressure law). 1 Describe and explain how changing the temperature of gas increases the gas pressure inside the container. Explain why gas cylinders should not be placed near heat sources. Evaluate newspaper articles of local fires that have involved gas canisters exploding and the reasons for the explosion in terms of gas pressure. Why do aerosol deodorants say: keep away from fire? what is happening inside a container of fixed volume when the temperature is changed. Investigate the Pressure law: a round-bottomed flask connected to a pressure gauge in a container of water. Heat the water taking the temperature and pressure. Plot a of pressure against temperature. BBC Bitesize – Temperature and gas calculations clip YouTube: