<p> Chapter 3 -Topic 3: Thermal physics SL.</p><p>Essential idea: Thermal physics deftly demonstrates the links between the macroscopic measurements essential to many scientific models with the microscopic properties that underlie these models.</p><p>3.1 – Thermal concepts Nature of science: 1.8 Evidence through experimentation: Scientists from the 17th and 18th centuries were working without the knowledge of atomic structure and sometimes developed theories that were later found to be incorrect, such as phlogiston and perpetual motion capabilities. Our current understanding relies on statistical mechanics providing a basis for our use and understanding of energy transfer in science.</p><p>Hamper – So far we have dealt with the motion of particles and, given their initial conditions, can predict their speed and motion at any time. Once we realize that all matter is made up of particles we can use this knowledge to build a model of the way those particles interact with each other. So, even though we can’t see these particles we can make predictions related to them. 1 U Molecular theory of solids, liquids and gases Explain the physical differences between the solid, liquid and gaseous phases in terms of molecular structure and particle motion 2 U Temperature and absolute temperature State that temperature determines the direction of thermal energy transfer between two objects A Using Kelvin and Celsius temperature scales and converting between them State the relation between the Kelvin (absolute) and Celsius scales of temperature and apply to typical conversions 3 U Internal energy A Describing temperature change in terms of internal energy DB −23 −1</p><p> where KB = Boltzmann’s constant = 1.38 × 10 J K </p><p>G (State that the) Internal energy is taken to be the total intermolecular potential energy + the total random kinetic energy of the molecules 4 U Specific heat capacity DB Q=mcΔT Define specific heat capacity A Applying the calorimetric techniques of specific heat capacity or specific latent heat Apply and describe calorimetric techniques of specific heat capacity experimentally experimentally Calculating energy changes involving specific heat capacity and specific latent heat of Solve problems involving specific heat capacity fusion and vaporization G The effects of cooling should be understood qualitatively but cooling correction calculations are not required 5 U Phase change A Describing phase change in terms of molecular behaviour Describe and explain the process of phase changes in terms of molecular behavior Sketching and interpreting phase change graphs G Phase change graphs may have axes of temperature versus time or temperature versus Describe and explain the process of phase changes and why temperature does not change energy during a phase change in terms of molecular behavior 6 U Specific latent heat DB Q=mL Define specific latent heat A Applying the calorimetric techniques of specific heat capacity or specific latent heat Apply and describe calorimetric techniques of specific latent heat experimentally experimentally Calculating energy changes involving specific heat capacity and specific latent heat of Solve problems involving specific latent heat of fusion and vaporization fusion and vaporization 7 U Conduction, convection and thermal radiation G Discussion of conduction and convection will be qualitative only Describe the thermal transfer mechanisms of conduction, convection and thermal radiation. Discussion of conduction is limited to intermolecular and electron collisions Discussion of convection is limited to simple gas or liquid transfer via density differences</p><p>Essential idea: The properties of ideal gases allow scientists to make predictions of the behaviour of real gases.</p><p>3.2 – Modelling a gas Nature of science: 4.1 Collaboration: Scientists in the 19th century made valuable progress on the modern theories that form the basis of thermodynamics, making important links with other sciences, especially chemistry. The scientific method was in evidence with contrasting but complementary statements of some laws derived by different scientists. Empirical and theoretical thinking both have their place in science and this is evident in the comparison between the unattainable ideal gas and real gases.</p><p>Hamper – a lot of experiments that you will do in the physics lab are designed to reinforce theory. However, real science isn’t always like that. Theories are often developed as a result of observation and experiment. Given that gases are made of randomly moving tiny particles it is not difficult to explain their properties. Deducing that gases are made of particles from the properties of the gas is a much more difficult proposition that will fortunately never have to be done again. </p><p>The pressure laws are examples of how we investigate the relationship between two variables while controlling all other factors. 1 U Mole, molar mass and the Avogadro constant DB 23 -1</p><p> n = N/NA where 𝑁A = Avogadro’s constant = 6.02 x 10 mol</p><p>Define the mole, molar mass and Avogadro constant 2 U Kinetic model of an ideal gas</p><p>G Students should be aware of the assumptions that underpin the molecular kinetic State the assumptions of the kinetic model of an ideal gas and explain the macroscopic theory of ideal gases behaviour of an ideal gas in terms of this model</p><p>2 3 U Pressure DB P = F/A Define pressure </p><p>4 U Equation of state for an ideal gas State the equation of state for an ideal gas DB</p><p>-1 -1</p><p> pV = nRT where R = Gas constant = 8.31 J K mol </p><p>A Solving problems using the equation of state for an ideal gas and gas laws Solve problems using the equation of state of an ideal gas</p><p>Sketching and interpreting changes of state of an ideal gas on pressure–volume, pressure–temperature and volume–temperature diagrams Investigate one of the gas laws (Boyle’s, Charles’s, Gay-Lusac) Investigating at least one gas law experimentally</p><p>G Gas laws are limited to constant volume, constant temperature, constant pressure and the ideal gas law</p><p>5 U Differences between real and ideal gases</p><p>G Students should understand that a real gas approximates to an ideal gas at Describe the difference between an ideal gas and a real gas conditions of low pressure, moderate temperature and low density</p>