P3 Particle Molecules & Matter PDF

Chapter 6: Molecules and matter Knowledge organiser Changes Changes of of state States of matter The relationship between temperature and pressure in gases Changes of state...

Chapter 6: Molecules and matter Knowledge organiser Changes Changes of of state States of matter The relationship between temperature and pressure in gases Changes of state and conservation of mass particles are spread out Changes of state are physical changes because no new almost no forces of attraction Gas temperature If the temperature of a gas in a sealed container is substances are produced. The mass always stays the Arrangement between particles The particles in a gas are constantly moving in increased, the pressure increases because same because the number of particles does not change. large distance between particles on random directions and with random speeds. the particles move faster so they hit the surfaces average The temperature of a gas is related to the average with more force Gas Particles and kinetic energy Movement particles move randomly at high speed kinetic energy of its particles. the number of these impacts per second increases, When the temperature of a substance is increased, the low density When a gas is heated, the particles gain kinetic exerting more force overall. kinetic energy store of its particles increases and the no fixed volume or shape energy and move faster, so the temperature of Properties the gas increases. particles vibrate or move faster. can be compressed and can flow spread out to fill all available space If the kinetic store of a substance’s particles increases If a gas is compressed quickly, for example, in a bicycle or decreases enough, the substance may change state. pump, its temperature can rise. This is because particles are in contact with each other Gas pressure The pressure a gas exerts on a surface, such as compressing the gas requires a force to be applied Density Arrangement forces of attraction between the walls of a container, is caused by the force of to the gas – this results in work being done to the particles are weaker than in solids You can calculate the density of an object if you know Liquid the gas particles hitting the surface. gas, since work done = force × distance particles are free to move randomly its mass and volume: Movement the energy gained by the gas is not transferred around each other The pressure of a gas produces a net force at right mass (kg) usually lower density than solids angles to the walls of a container or any surface. quickly enough to its surroundings. density (kg/m3) = volume (m3) Properties fixed volume m shape is not fixed so they can flow = V L particles held next to each other in Arrangement fixed positions by strong forces of attraction Internal energy Movement particles vibrate about fixed positions Solid Heating a substance increases its internal energy. high density Internal energy is the sum of the total kinetic energy fixed volume Properties the particles have due to their motion and the total fixed shape (unless deformed by potential energy the particles have due to their an external force) positions relative to each other. Latent heat In a graph showing the change in temperature of a The energy transferred when a substance changes state is substance being heated or cooled, the flat horizontal called the latent heat. sections show when the substance is changing state. Specific latent heat – the energy required to change 1 kg The energy transfers taking place during a change in of a substance with no change in temperature. state do not cause a change in temperature, but do Specific latent heat of fusion – the energy required to change the internal energy of the substance. melt 1 kg of a substance with no change in temperature. temperature Specific latent heat of vaporisation – the energy required to evaporate 1 kg of a substance with no change in boiling boiling gas temperature. point The energy needed to change the state of a substance can Key terms heating be calculated using the equation: Write a definition for these key terms. liquid melting melting thermal energy for specific boiling condensation conservation of mass density evaporation freezing fusion mass point a change in state = × latent heat (J) (kg) (J/kg) internal energy latent heat melting specific latent heat sublimation vaporisation solid time E=m×l Chapter 6: Molecules and matter Retrieval questions Learn the answers to the questions below then cover the answers column with a piece of paper and write as many as you can. Check and repeat. P6 questions Answers Which two quantities do you need to measure to 1 mass and volume Put paper here find the density of a solid or liquid? What happens to the particles in a substance if its they move faster and the energy in their kinetic energy 2 temperature is increased? store increases no new substances are produced and the substance 3 Why are changes of state physical changes? will have the same properties as before if the change Put paper here is reversed Why is the mass of a substance conserved when it 4 the number of particles does not change changes state? the total kinetic energy and potential energy of all the 5 What is the internal energy of a substance? particles in the substance Put paper here Why does a graph showing the change in temperature the energy transferred during a change in state causes a 6 as a substance cools have a flat section when the change in the internal energy of the substance substance is changing state? What is the name given to the energy transferred when 7 latent heat Put paper here a substance changes state? the energy required to change the state of one kilogram of 8 What is the specific latent heat of a substance? that substance with no change in temperature the energy required to change one kilogram of the 9 What is the specific latent heat of fusion a substance? substance from solid to liquid at its melting point, Put paper here without changing its temperature the energy required to change one kilogram of the What is the specific latent heat of vaporisation of a 10 substance from liquid to vapour at its boiling point, substance? without changing its temperature On a graph of temperature against time for a Put paper here the time when the substance is changing state and the 11 substance being heated up or cooled down, what do temperature is not changing the flat (horizontal) sections show? What property of a gas is related to the average kinetic 12 temperature energy of its particles?